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TSO/E REXX User's Guide

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1. PARSE VAR phrase partl part2 template containing comma as string separator part1 contains To be part2 contains or not to be In this example notice that the comma is not included with To be because the comma is the string separator Variable When you do not know in advance what string to specify as separator in a template you can use a variable enclosed in parentheses The variable value must be included in the data separator phrase To be or not to be PARSE VAR phrase part1 separator part2 part1 contains To be part2 contains or not to be Again in this example notice that the comma is not included with To be because the comma is the string separator 7 6 OS 390 V1R2 0 TSO E REXX User s Guide Parsing Data Number You can use numbers in a template to indicate the column at which to separate data An unsigned integer indicates an absolute column position and a signed integer indicates a relative column position Absolute column position An unsigned integer or an integer prefixed with an equal sign 2 in a template separates the data according to absolute column position The first segment starts at column 1 and goes up to but does not include the information in the column number specified The subsequent segments start at the column numbers specified quote Ignorance is bliss PARSE VAR quote partl 5 part2 part1 contains Igno
2. EXECIO 1 DISKR indd Read 1 line to the data stack return code rc Save execio rc IF return_code 0 THEN Get a line ok x DO Yes in ctr in ctr 1 Increment input line ctr x PARSE PULL line 1 Pull line just read from stack IF LENGTH line 1 gt 10 then If line linger than 10 chars DO EXECIO 1 DISKW outdd STEM line Write it to outdd out ctr out ctr 1 Increment output line ctr END END END EXECIO 0 DISKR indd FINIS Close the input file indd IF out ctr 0 THEN Were any lines written to outdd DO Yes So outdd is now open Figure 12 5 EXECIO Example 5 12 16 05 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information r EXECIO Example 5 continued BRR see KR REA KR RRA KKK EK KKK EKER IKK k Kk k k k k k k k KEI k kkk kkk Since the outdd file is already open at this point the x following EXECIO 0 DISKW command will close the file but will not empty it of the lines that have already been x written The data set allocated to outdd will contain out ctr lines BKK k kek k e ke e e k e e k k kke k k k e ERK e k k K ke k k k k k k k k k k K k k k k k k k k k k kkk k k k kk kkk EXECIO DISKW outdd FINIS Closes the open file outdd SAY File outdd now contains out ctr lines END ELSE Else no new lines have been written to file outdd DO Erase any old re
3. Hello What s your name 7 PULL who Get the person s name IF who THEN SAY Hello stranger ELSE SAY Hello who IRX00061 Error running REXX EXEC HELLO line 7 Unmatched or quote ck The exec runs until it detects the error a missing at the end of the comment As a result the SAY instruction displays the question but doesn t wait for your response because the next line of the exec contains the syntax error The exec ends and the language processor displays error messages The first error message begins with the line number of the statement where the error was detected followed by three pluses and the contents of the statement 7 PULL who Get the person s name IF who THEN SAY Hello stranger ELSE SAY Hello who The second error message begins with the message number followed by a message containing the exec name line where the error was found and an explanation of the error IRX00061 Error running REXX EXEC HELLO line 7 Unmatched or quote For more information about the error you can go to the message explanations in TSO E Messages GC28 1978 where information is arranged by message number To fix the syntax error in this exec add to the end of the comment on line 7 PULL who Get the person s name Preventing Translation to Uppercase As a rule all alphabetic characters processed by the language processor are translated to uppercase before they are processed
4. 2 0 0 0 lll 2 13 Preventing Translation to Uppercase 2 14 From Within an Exec loss 2 15 As Input to an Exec 2 sss 2 15 Exercises Running and Modifying the Example Execs 2 16 Passing Information to an Exec 1 llle 2 16 Using Terminal Interaction 0 2220000 2 16 Specifying Values when Invoking an Exec 2 17 Specifying Too Few Values llle 2 17 Specifying Too Many Values 2 17 Preventing Translation of Input to Uppercase 2 18 Exercises Using the ARG Instruction 2 18 Passing Arguments s 2 19 Passing Arguments Using the CALL Instruction or REXX Function Call 2 19 Passing Arguments Using the EXEC Command 2 19 This chapter introduces execs and their syntax describes the steps involved in writing and running an exec and explains concepts you need to understand to avoid common problems Before You Begin Before you can write a REXX program called an exec you need to create a data set to contain the exec The data set can be either sequential or partitioned but if you plan to create more than one exec it is easier to create a REXX library as a partitioned data set PDS with execs as members Copyright IBM Corp 1988 1996 2 1 What is a REXX Exec To create a PDS allocate a data set with your prefix usually your user ID as the first qua
5. Function Meaning Code 0 Normal completion 4 Some data set information is unavailable All data set information other than directory information can be considered valid 16 Severe error occurred None of the variables containing information about the data set can be considered valid The following variables are set to the attributes of the data set specified Variable Contents SYSDSNAME Data set name SYSVOLUME Volume serial ID SYSUNIT Device unit on which volume resides SYSDSORG Data set organization PS PSU DA DAU IS ISU PO POU VS SYSRECFM Record format three character combination of the following U F V T B S A M SYSLRECL Logical record length SYSBLKSIZE Block size SYSKEYLEN Key length SYSALLOC Allocation in space units SYSUSED Allocation used in space units Chapter 10 Using TSO E External Functions 10 3 TSO E External Functions Variable Contents SYSUSEDPAGES Used space of a partitioned data set extended PDSE in 4K pages SYSPRIMARY Primary allocation in space units SYSSECONDS Secondary allocation in space units SYSUNITS Space units CYLINDER TRACK BLOCK SYSEXTENTS Number of extents used SYSCREATE Creation date Year day format for example 1985 102 SYSREFDATE Last referenced date Year day format for example 1985 107 Specifying DIRECTORY causes the date to
6. 8 11 Determining the Active Host Command Environment 8 11 Checking if a Host Command Environment is Available 8 11 Examples Using the ADDRESS Instruction 8 12 This chapter describes how to issue TSO E commands and other types of commands from a REXX exec Types of Commands A REXX exec can issue many types of commands The two main categories of commands are e TSO E REXX commands Commands provided with the TSO E implementation of the language These commands do REXX related tasks in an exec such as Control I O processing of information to and from data sets EXECIO Perform data stack services MAKEBUF DROPBUF QBUF QELEM NEWSTACK DELSTACK QSTACK Change characteristics that control the execution of an exec EXECUTIL and the immediate commands Check for the existence of a host command environment SUBCOM More information about these TSO E REXX commands appears throughout the book where the related task is discussed Host commands The commands recognized by the host environment in which an exec runs A REXX exec can issue various types of host commands as discussed in the remainder of this chapter When an exec issues a command the REXX special variable RC is set to the return code An exec can use the return code to determine a course of action within the exec Every time a command is issued RC is set Thus RC contains the return code from the mos
7. ALLOC DA newds NEW SPACE newprimary sysseconds LIKE baseds Allocate the new data set IF RC 0 THEN If return code from allocate is 0 SAY Data set newds was allocated ELSE SAY Data set newds was not allocated Return code was RC Chapter 10 Using TSO E External Functions 10 13 Additional Examples r Example 2 Part 1 Using the OUTTRAP Function kkkkkkkkkkkkkkkkkkkkkkkkkkxkxk REXX RRR RRR kk kkk kkk k kkk k k RRA kkk k ERE kk This exec adds a data set to the front of the data sets in the SYSPROC concatenation It first asks for the name of the data set to add then it finds all data sets currently allocated to SYSPROC adds the new data set to the beginning and re allocates the concatenation to SYSPROC x RR RR RRR RRR REE R RE e kk KERIKERI KERIKERI KK KE AA KKK IARI k kk kkk k kkk kk SAY Enter the fully qualified data set name you want added SAY to the beginning of the SYSPROC concatenation Do NOT SAY place quotation marks around the data set name PULL addname x OUTTRAP name Begin trapping lines of output from commands Output goes to variables beginning with name LISTA ST List the status of your currently allocations found NO Set the found flag to no i l Set the index variable to 1 RR RAR RRR ER RRR ERR RE e kk REI kk k k k e kk ke k k KEIRA IKKE KKK k kk kkk k ER ERE Loop through the lines
8. This example results in the following error message MISSING DATA SET NAME INVALID KEYWORD kkk If an exec includes trace c and again incorrectly issues the LISTDS command the exec displays the line number and the command executes it and displays the error message and the return code from the command as follows 3 LISTDS gt gt gt LISTDS MISSING DATA SET NAME INVALID KEYWORD RC 12 kkk TRACE E When you specify trace e in an exec any host command that results in a nonzero return code is traced after it executes and the return code from the command is displayed If an exec includes trace e and again issues the previous incorrect LISTDS command the exec displays error messages the line number and the command and the return code from the command as follows MISSING DATA SET NAME INVALID KEYWORD 3 LISTDS RC 12 kkk For more information about the TRACE instruction see TSO E REXX Reference SC28 1975 9 2 09 390 V1R2 0 TSO E REXX User s Guide Debugging Execs Using REXX Special Variables RC and SIGL As mentioned earlier the REXX language has three special variables RC SIGL and RESULT These variables are set by the system during particular situations and can be used in an expression at any time If the system did not set a value a special variable displays its name as do other variables in REXX You can use two of these special variabl
9. Comparisons Between CLIST and REXX contains tables that compare the CLIST language with the REXX language Terminology Throughout this book a REXX program is called an exec to differentiate it from other programs you might write such as CLISTs The command to run an exec in TSO E is the EXEC command To avoid confusion between the two this book uses lowercase and uppercase to distinguish between the two uses of the term exec References to the REXX program appear as exec and references to the TSO E command appear as EXEC O Copyright IBM Corp 1988 1996 xiii Purpose of Each Chapter At the beginning of each chapter is a statement about the purpose of the chapter Following that are headings and page numbers where you can find specific information Examples Throughout the book you will find examples that you can try as you read If the example is a REXX keyword instruction the REXX keyword is in uppercase Information that you can provide is in lowercase The following REXX keyword instruction contains the REXX keyword SAY which is fixed and a phrase which can vary SAY This is an example of an instruction Similarly if the example is a TSO E command the command name and keyword operands which are fixed are in uppercase Information that can vary such as a data set name is in lowercase The following ALLOCATE command and its operands are in uppercase and the data set and file name are in lowercase ALLOCATE DATA
10. code goes to amp LASTCC RETURN instruction call somesub var answer RESULT exit somesub arg vl vafue 4 vl 3 return value value goes to RESULT x Performing File I O CLIST REXX Reading from a file Reading from a file OPENFILE GETFILE CLOSFILE statements OPENFILE PAYCHEKS EXECIO DISKR EXECIO DISKRU commands EXECIO 3 DISKR indd stem employee FINIS CLOSFILE PRICES SET COUNTER 1 Read 3 records from the data set in indd DO WHILE amp COUNTER V 3 The 3 records go to a list of compound x GETFILE PAYCHEKS variables with the stem of employee They SET EMPLOYEE amp COUNTER amp PAYCHEKS are employee 1 employee 2 and employee 3 SET COUNTER amp COUNTER 1 END CLOSFILE PAYCHEKS Writing to a file Writing to a file OPENFILE PUTFILE CLOSFILE statements EXECIO DISKW OPENFILE PRICES OUTPUT push 2590 00 put amount on data stack SET PRICES 2590 00 EXECIO 1 DISKW outdd finis PUTFILE PRICES Write from data stack to data set in outdd C 6 08 390 V1R2 0 TSO E REXX User s Guide Syntax CLIST REXX Continuing a statement over more than one line Continuing an instruction over more than one line Use or IF amp STR SYSDATE amp STR 10 13 87 THEN WRITE On amp SYSDATE the system was down Use say This instruction covers two lines Separating statements within a line
11. ss 4 14 DO WHILE EoopS 5 nt see oe tee Ae ee ee 3 4 14 Exercise Using a DO WHILE Loop 4 15 DO UNTIE Loops 444 34 puede Pid vo bee eR quie t 4 16 Exercise Using a DO UNTIL Loop 4 17 Combining Types of Loops 2000500004 4 17 Nested DO Loops ls 4 18 Exercises Combining Loops aaa aaa aa 4 19 Using Interrupt Instructions oaa aa a 4 20 EXIT Instruction 2e 4 20 CALL RETURN Instructions sls 4 21 SIGNAL Instruction ss 4 22 This chapter introduces instructions that alter the sequential execution of an exec and demonstrates how those instructions are used Generally when an exec runs one instruction after another executes starting with the first and ending with the last The language processor unless told otherwise executes instructions sequentially You can alter the order of execution within an exec by using specific REXX instructions that cause the language processor to skip some instructions repeat others or jump to another part of the exec These specific REXX instructions can be classified as follows Conditional instructions which set up at least one condition in the form of an expression If the condition is true the language processor selects the path following that condition Otherwise the language processor selects another path The REXX conditional instructions are IF expression THEN ELSE SELECT WHEN expression OTHERWISE
12. Issuing Other Types of Commands from an Exec r ADDRESS Example 3 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR RRR RRR KEIR k kkk kkk k ERE kk This exec must be run in ISPF It displays panel named newtool and gets the name of a data set from input fields named ntproj ntgroup nttype and ntmem If no member name is specified thex data set is sequential the data set name does not include it If a member name is specified the member is added to data set name The fully qualified data set name is then inserted into a TRANSMIT command that includes single quotation marks and the destination which was received from an input field named ntdest RR RAR RRR kde deed ee k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk ADDRESS ispexec DISPLAY PANEL newtool ADDRESS tso re establish the TSO host command environment IF ntmem THEN member name is blank DO dsname ntproj m ntgroup nttype TRANSMIT ntdest DA dsname END ELSE DO dsname ntproj ntgroup nttype ntmem TRANSMIT ntdest DA dsname END or r ADDRESS Example 4 To link to or attach a logoff routine named MYLOGOFF and pass it the level of TSO E installed you can issue the following instructions from an exec ADDRESS LINK MYLOGOFF SYSVAR SYSTSOE ADDRESS ATTACH MYLOGOFF SYSVAR SYSTSOE Chapter 8 Entering Commands from an Exec 8 13 Issuing
13. Multiplication and division Addition and subtraction Thus the preceding example would be evaluated in the following order 1 Expression in parentheses 7 2 9 3 1 X df 3 2 Multiplication 7 2 3 1 Mt 6 3 Addition and subtraction from left to right 7 6 1 212 Using Arithmetic Expressions You can use arithmetic expressions in an exec many different ways The following example uses several arithmetic operators to round and remove extra decimal places from a dollar and cents value Example Using Arithmetic Expressions RR kk RRR EER RRR ERR ERIK k k k k kk k k REXX KK k E A k Kk A A k k k k k k k k k k k k kk kkk This exec computes the total price of an item including sales tax rounded to two decimal places The cost and percent of the tax expressed as a decimal number are passed to the exec when it is run x RR RRR RRR ERR RR ERR RRR e kk e ke k k kk k k k e kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk PARSE ARG cost percent_tax total cost cost percent_tax Add tax to cost price total 100 5 1 100 Round and remove x extra decimal places SAY Your total cost is price 3 6 05 390 V1R2 0 TSO E REXX User s Guide Using Expressions Exercises Calculating Arithmetic Expressions 1 What will the following program display on the screen Exercise kkk RRR kkk kkk k kkk kkk kkk kkk kkk RE
14. Using REXX in TSO E and Other MVS Address Spaces on page 13 1 Features of REXX In addition to its versatility REXX has many other features some of which are Ease of use The REXX language is easy to read and write because many instructions are meaningful English words Unlike some lower level programming languages that use abbreviations REXX instructions are common words such as SAY PULL IF THEN ELSE DO END and EXIT Copyright IBM Corp 1988 1996 1 1 Components of REXX Free format There are few rules about REXX format You need not start an instruction in a particular column you can skip spaces in a line or skip entire lines you can have an instruction span many lines or have multiple instructions on one line variables do not need to be predefined and you can type instructions in upper lower or mixed case The few rules about REXX format are covered in Syntax of REXX Instructions on page 2 3 Convenient built in functions REXX supplies built in functions that perform various processing searching and comparison operations for both text and numbers Other built in functions provide formatting capabilities and arithmetic calculations Debugging capabilities When a REXX exec running in TSO E encounters an error messages describing the error are displayed on the screen In addition you can use the REXX TRACE instruction and the interactive debug facility to locate errors in execs I
15. numberl 5 number2 10 DO i 1 T05 CALL subroutine SAY answer Displays 105 END EXIT subroutine DO i 1 T05 answer numberl number2 numberl number2 number2 answer END RETURN To avoid this kind of problem in an internal subroutine you can use The PROCEDURE instruction as described in the next topic e Different variable names in a subroutine and pass arguments on the CALL instruction as described in Passing Information by Using Arguments on page 6 6 Protecting Variables with the PROCEDURE Instruction When you use the PROCEDURE instruction immediately after the subroutine label all variables used in the subroutine become local to the subroutine and are shielded from the main part of the exec You can also use the PROCEDURE EXPOSE instruction to protect all but a few specified variables The following two examples show the differing results when a subroutine uses the PROCEDURE instruction and when it doesn t Example Using the PROCEDURE Instruction kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX K deeietekekeoetekejekdetekekekekeekekejekeeeieieex This exec uses a PROCEDURE instruction to protect the variables within its subroutine E kk k k e e ek e ke k k kk k k k e kk de k k k kk k k k k kk e k k k kk k k k KKK k k k k kk k k k kkk kkk k kkk kk numberl 10 CALL subroutine SAY numberl number2 displays 10 NUMBER2 EXIT subroutine PROCEDURE numberl 7 number2
16. DO i 1 T06 SAY Enter an employee name PARSE PULL employee i END If you entered the same names used in the previous example of an array you would have a group of compound variables as follows employee 1 Adams Joe employee 2 Crandall Amy employee 3 Devon David employee 4 Garrison Donna employee 5 Leone Mary employee 6 Sebastian Isaac When the names are in the group of compound variables you can easily access a name by its number or by a variable that represents its number name 3 SAY employee name Displays Devon David For more information about compound variables see TSO E REXX Reference SC28 1975 Using Stems When working with compound variables it is often useful to initialize an entire collection of variables to the same value You can do this easily with a stem A stem is the first variable name and first period of the compound variable Thus every compound variable begins with a stem The following are stems FRED Array employee You can alter all the compound variables in an array through the stem For example to change all employee names to Nobody issue the following assignment instruction employee Nobody As a result all compound variables beginning with employee whether or not they were previously assigned return the value Nobody Compound variables that are assigned after the stem assignment are not affected 7 2 OS 390 V1R2 0 TSO
17. SYSPROC is a system file whose data sets can contain both CLISTs and execs Execs are distinguished from CLISTs by the REXX exec identifier a comment at the beginning of the exec the first line of which includes the word REXX SYSEXEC is a system file whose data sets can contain only execs Your installation might have changed the name to something other than SYSEXEC but for the purposes of this book we will call it SYSEXEC When both system files are available SYSEXEC is searched before SYSPROC Allocating a PDS to a System File To allocate the PDS that contains your execs to a system file you need to do the following Decide if you want to use the separate file for execs SYSEXEC or combine CLISTs and execs in the same file SYSPROC For information that will help you decide see Things to Consider When Allocating to a System File SYSPROC or SYSEXEC on page 13 4 Use one of the following two checklists for a step by step guide to writing an exec that allocates a PDS to a system file Checklist 3 Writing an Exec that Sets up Allocation to SYSEXEC on page A 10 Checklist 4 Writing an Exec that Sets up Allocation to SYSPROC on page A 12 After your PDS is allocated to the system file you can then run an exec by simply typing the name of the data set member that contains the exec You can type the member name in any of the following locations At the READY prompt READY timegame From
18. To set the language to Japanese for subsequent REXX message displays issue the SETLANG function followed by the 3 character code JPN enclosed within parentheses oldlang SETLANG JPN oldlang is set to the previous language setting The current setting is set to JPN The SETLANG function can be used in REXX execs that run in any MVS address space Using the STORAGE Function You can use the STORAGE function to retrieve data from a particular address in storage You can also use the STORAGE function to place data into a particular address in storage The STORAGE function can be used in REXX execs that run in any MVS address space Using the SYSCPUS Function The SYSCPUS function places in a stem variable information about those CPUs that are online The SYSCPUS function runs in any MVS address space Example Consider a system with two online CPUs Their serial numbers are FF0000149221 and FF1000149221 Assuming you issue the following sequence of statements REXX x SYSCPUS cpus SAY 0 if function performed okay SAY Number of online CPUs is cpus O DO i 1 TO CPUS 0 SAY CPU i has CPU info cpus i END X 10 8 os 390 V1R2 0 TSO E REXX User s Guide TSO E External Functions you get the following output 0 if function performed okay 0 Number of online CPUs is 2 CPU 1 has CPU info FF0000149221 CPU 2 has CPU info FF1000149221 1 x 4 digits model numbe
19. Using Conditional Instructions SELECT WHEN OTHERWISE END Instruction To select one of any number of choices use the SELECT WHEN OTHERWISE END instruction In a flowchart it appears as follows SELECT THEN WHEN True y instruction gt False WHEN THEN True gt instruction gt False WHEN THEN True gt instruction gt ozis False OTHERWISE gt instruction s _ gt END 1 As a REXX instruction the flowchart example looks like SELECT WHEN expression THEN instruction WHEN expression THEN instruction WHEN expression THEN instruction OTHERWISE instruction s END The language processor scans the WHEN clauses starting at the beginning until it finds a true expression After it finds a true expression it ignores all other possibilities even though they might also be true If no WHEN expressions are true it processes the instructions following the OTHERWISE clause As with the IF THEN ELSE instruction when you have more than one instruction for a possible path begin the set of instructions with a DO and end them with an END However if more than one instruction follows the OTHERWISE keyword DO and END are not necessary 4 6 OS 390 V1R2 0 TSO E REXX User s Guide BABIES GIRLS BOYS TEENAG WOMEN MEN SELECT WHEN age lt status WHEN age lt DO IF sex stat ELSE stat END WHEN
20. Variable value The data traced is the contents of a variable gt L gt Literal value The data traced is a literal string uninitialized variable or constant 20 Operation result The data traced is the result of an operation on two terms 3 14 09 390 V1R2 0 TSO E REXX User s Guide Tracing Expressions with the TRACE Instruction The following example uses the TRACE instruction EDIT USERID REXX EXEC SAMPLE COLUMNS 009 080 COMMAND gt SCROLL gt HALF dexekkeek kkkkkkkkkkkkkkkkkkkkkkkkkk TOP OF DATA eeseseseese eek dee ee kde dee dee jede dee 000001 333x 3 0000006 amp REXX k k kkk kkk kkk kkk kkk kkk kkk 000002 This exec uses the TRACE instruction to show how an x 000003 expression is evaluated operation by operation x 000004 xxx scc eee ee eee eee eee keeekekeeekekekeekekekeelekekeeekeieeeeieek x 000005 x 9 000006 y 2 000007 TRACE I 000008 000000 IF x 1 gt 5 y THEN 000010 SAY x is big enough 000011 ELSE NOP No operation on the ELSE path dekckekekeek kkkkkkkkkkkkkkkkkkkkkkx BOTTOM OF DATA sexes dee ke ke ke ek ke jede ke dee When you run the example you see on your screen 9 x x IF x 1255 y gt gt n 9 L gt L gt n 1 L gt 0 gt n 10 n gt L gt n 5 n gt gt n 2 L gt 0 gt L 10 u gt 0 gt L 0 First you see the line number 9 followed by the expression Then the
21. You can use a DO WHILE loop instead of the DO FOREVER loop in the example using the LEAVE Instruction on page 4 12 However you need to initialize the loop with a first case so the condition can be tested before you get into the loop Notice the first case initialization in the beginning three lines of the following example r Example Using DO WHILE kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX XK RRR RRR RRR KERR RK kkk kkk kkk kk This exec uses a DO WHILE loop to send data sets to the system printer x RR RR RRR RRR RRR ERR RRR EAR ERIK REA KERRI kk k k k k kk k k k k kk A k k k kk kkk EERE RE SAY Enter the name of a data set to print SAY If there are no data sets enter QUIT PULL dataset name DO WHILE dataset name QUIT PRINTDS DA dataset name SAY dataset name printed SAY Enter the name of the next data set SAY When there are no more data sets enter QUIT PULL dataset name END SAY Good bye 4 14 09 390 V1R2 0 TSO E REXX User s Guide Using Looping Instructions Exercise Using a DO WHILE Loop Write an exec with a DO WHILE loop that asks passengers on a commuter airline if they want a window seat and keeps track of their responses The flight has 8 passengers and 4 window seats Discontinue the loop when all the window seats are taken After the loop ends display the number of window seats taken and the number of passengers questioned ANSWER r Possible
22. les 10 7 Using the SETLANG Function llle 10 7 Using the STORAGE Function 10 8 Using the SYSCPUS Function llle 10 8 Using the SYSDSN Function 2 0 10 9 Using the SYSVAR Function 2 20 24 10 10 User Information 2 ssec XE be A Sa SS ns 10 10 Terminal Information a 10 11 Language Information ole 10 11 Exec Information oes 10 11 System Information 2000000000022 ee 10 11 Console Session Information 10 12 Additional Examples segria g ea i e es 10 13 Function Packages s 10 17 Search Order for Functions oll len 10 17 This chapter shows how to use TSO E external functions and describes function packages TSO E External Functions In addition to the built in functions TSO E provides external functions that you can use to do specific tasks Some of these functions perform the same services as control variables in the CLIST language The TSO E external functions are e GETMSG returns in variables a system message issued during an extended MCS console session It also returns in variables associated information about the message The function call is replaced by a function code that indicates whether the call was successful LISTDSI returns in variables the data set attributes of a specified data set The function call is replaced by a function code that indicates whether the call
23. part2 contains rance is bliss This example could have also been coded as follows Note the explicit use of the column 1 indicator prior to part1 that was implied in the previous example and the use of the 5 part2 to indicate the absolute position column 5 quote Ignorance is bliss PARSE VAR quote 1 partl 5 part2 partl contains Igno part2 contains rance is bliss When a template has more than one number and a number at the end of the template is lower than an earlier number parse loops back to the beginning of the data quote Ignorance is bliss PARSE VAR quote partl 5 part2 10 part3 1 part4 part1 contains Igno part2 contains rance part3 contains is bliss part4 contains Ignorance is bliss When each variable in a template has column numbers both before and after it the two numbers indicate the beginning and the end of the data for the variable quote Ignorance is bliss PARSE VAR quote 1 part1 10 11 part2 13 14 part3 19 1 part4 20 partl contains Ignorance part2 contains is part3 contains bliss part4 contains Ignorance is bliss e Relative column position A signed integer in a template separates the data according to relative column position that is a starting position relative to the starting position of the preceding part A signed integer can be either positive or negative causing the part to be pars
24. Arithmetic Operators 2 2 aaa a 3 4 Comparison Operators les 3 7 Logical Boolean Operators 20 00000504 3 10 Concatenation Operators 0 0 0 0 00 eee ee 3 12 Priority of Operators aaa aaa 3 12 Tracing Expressions with the TRACE Instruction 3 14 Chapter 4 Controlling the Flow Within an Exec 4 1 Using Conditional Instructions oll 4 2 IF THEN ELSE Instructions 2020020020005 4 2 Nested IF THEN ELSE Instructions 0 4 3 SELECT WHEN OTHERWISE END Instruction 4 6 Using Looping Instructions 0 00000 pee 4 8 Repetitive Loops 4 8 Conditional Loops ss 4 14 Combining Types of Loops les 4 17 Nested DO Loops ss 4 18 Using Interrupt Instructions 2 0 0000002000 4 20 EXIT Instruction e 4 20 CALL RETURN Instructions aa 4 21 SIGNAL INStMUGHON oso scr deox mE EX 3 bees 4 22 Chapter 5 Using Functions 0 5 1 What is a Function aaa aaa 5 1 Example ofa Function 02 EA E E ee ee 5 3 Built In Functions 2 2 ap aa ee 5 4 Arithmetic Functions 0 ls 5 4 Comparison Functions ls 5 5 Conversion Functions 22s 5 5 Formatting Functions es 5 5 String Manipulating Functions lll lien 5 6 Miscellaneous Functions a 5 7 Testing Input
25. LANRES MVS V1R3 1 LANRES base e IBM LAN Server for MVS V1R1 LAN Server base About This Book XV Product Name and Level Name in OS 390 Base or Optional MICR OCR Support e MICR OCR Support base OpenEdition MVS Services OpenEdition MVS Services base OpenEdition MVS Debugger OpenEdition MVS Debugger base OpenEdition MVS Shell amp Utilities OpenEdition MVS Shell amp Utilities base OpenEdition DCE Base Services OSF OpenEdition DCE Base Services base DCE level 1 1 OpenEdition DCE Distributed File Service OpenEdition DCE Distributed File Service base DFS OSF DCE level 1 0 3a DFS OpenEdition DCE User Data Privacy OpenEdition DCE User Data Privacy optional e SOMobjects Application Development e SOMobjects Application Development optional Environment ADE V1R1 Environment ADE e SOMobjects Runtime Library RTL e SOMobjects Runtime Library RTL base e SOMobjects service classes e SOMobjects service classes base Open Systems Adapter Support Facility Open Systems Adapter Support Facility base OSA SF R1 OSA SF MVS ESA RMF V5R2 RMF optional RACF V2R2 Security Server optional e RACF OpenEdition DCE Security Server SDSF V1R6 SDSF optional SMP E V1R8 1 SMP E base SystemView for MVS Base SystemView for MVS Base base IBM TCP IP V3R2 TCP IP base e TCP IP CICS Sockets TCP IP CICS Sockets optional TCP IP IMS Sockets TCP IP IMS Sockets optional TCP IP Kerberos TC
26. RETURN Chapter 6 Writing Subroutines and Functions 6 3 Writing a Subroutine To determine whether to make a subroutine internal or external you might consider factors such as e Size of the subroutine Very large subroutines often are external whereas small subroutines fit easily within the calling exec How you want to pass information It is quicker to pass information through variables in an internal subroutine This method is described in Passing Information by Using Variables on page 6 4 Whether the subroutine might be of value to more than one exec or user If so an external subroutine is preferable Passing Information to a Subroutine An internal subroutine can share variables with its caller Therefore you can use commonly shared variables to pass information between caller and internal subroutine You can also use arguments to pass information to and from an internal subroutine External subroutines however cannot share the same variables and information must pass between them through arguments or some other external way such as the data stack Passing Information by Using Variables When an exec and its internal subroutine share the same variables the value of a variable is what was last assigned regardless of whether the assignment was in the main part of the exec or in the subroutine In the following example the value of answer is assigned in the subroutine and displayed in the main part
27. Separating instructions within a line No more than one statement per line Use do 5 Say Hello end Character set of statements Character set of instructions Must be in uppercase Can be upper lower or mixed case Comments Comments Enclose between closing delimiter optional at the end of a line Enclose between closing delimiter always required Using Functions CLIST REXX Calling a function Calling a function amp FUNCTION expression function arguments SET A amp LENGTH ABCDE 8A 5 x a length abcde a 5 Using Variables CLIST REXX Assigning value to a variable Assigning value to a variable SET statement assignment instruction SET X 5 amp X gets the value 5 x x25 X gets the value 5 x SET NUMBER 8X amp NUMBER gets the value 5 NUMBER x NUMBER gets the value 5 SET Y NUMBER amp Y gets the value NUMBER Y number Y gets the value number Appendix C Comparisons Between CLIST and REXX C 7 C 8 08 390 V1R2 0 TSO E REXX User s Guide Index Special Characters 3 5 3 5 3 5 3 5 V 3 10 2 13 3 5 3 8 9 8 3 8 3 8 gt 3 8 gt lt 3 8 gt 3 8 gt gt gt final result 3 15 gt L gt literal value 3 14 gt O gt operation result 3 14 gt V gt variable value 3 14 3 10 A ADDRESS built in function 8 11 ADDRESS ins
28. To have TSO E commands prompt you when the commands are issued from within an exec you can do one of two things e Run the exec explicitly with the EXEC command and use the PROMPT operand EXEC mynew exec create exec prompt Use the PROMPT function within the exec Because PROMPT is a function it is used as an expression within an instruction such as an assignment instruction or a SAY instruction To turn prompting on write saveprompt PROMPT ON saveprompt is set to the previous setting of PROMPT x To turn prompting off write x PROMPT OFF x is set to the previous setting of PROMPT x To find out the prompting status write SAY PROMPT displays either ON or OFF To reset prompting to a specific setting saved in variable saveprompt write X prompt saveprompt Important Note Neither of these options can override a NOPROMPT operand in your TSO E profile Your TSO E profile controls prompting for all commands issued in your TSO E session whether the commands are issued in line mode in ISPF in an exec or in a CLIST To display your profile issue the PROFILE command To change a profile from NOPROMPT to PROMPT issue PROFILE PROMPT Prompting by commands also depends on whether there are elements in the data stack If the data stack contains an element the user at the terminal is not prompted because the data stack element is used in response to the prompt For more in
29. or close a file It reads records from file indd allocated to sams input dataset and writes selected records to file x outdd allocated to sams output dataset In this example the data set smas input dataset contains variable length records RECFM VB x RR kk RRR RRR RRR ERR RRR RIK e ke k k kk k k k e k k ke k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk FREE FI outdd FREE FI indd ALLOC FI outdd DA sams output dataset OLD REUSE ALLOC FI indd DA sams input dataset SHR REUSE eofflag 2 Return code to indicate end of file return code 0 Initialize return code in_ctr 0 Initialize of lines read x out ctr 0 Initialize of lines written x RR kk RRR RR RRR ERR KERIKERI RIA KERIKERI KKK AI KIKI k k k kkk kkk k kkk kk Open the indd file but do not read any records yet All x records will be read and processed within the loop body x RR RAR RRR ERE RR ERR RRR RIK ee k k kk k k dede k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk EXECIO 0 DISKR indd OPEN Open indd x RR RAR RRR ERR REE dee k e kk e k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk Now read all lines from indd starting at line 1 and copy x selected lines to outdd x RR RRR RRR RRR e e kek e ke k e IKKE KARRI ARK AK RRA KKK AK KKK IKK k kk kkk k kkk kk DO WHILE return code eofflag Loop while not end of file
30. queue a null line at the bottom of the stack to indicate the end of the information QUEUE If there are null lines lines of length 0 throughout the data and the data stack is not shared you can assign the built in QUEUED function to a variable to indicate the number of items on the stack n QUEUED EXECIO n DISKW outdd FINIS 12 6 oSs 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information How to access the data set An O data set must first be allocated to a ddname The ddname does not need to exist previously In fact it might be better to allocate to a new ddname such as MYOUTDD in order not to interfere with previously established allocations You can allocate from within the exec with the ALLOCATE command as shown in the following example or you can allocate before the exec runs ALLOC DA out data F myoutdd OLD REUSE EXECIO DISKW myoutdd Options for DISKW Options you can use are OPEN To open a data set When you specify OPEN with EXECIO 0 it opens the data set and positions the file position pointer before the first record EXECIO DISKW myoutdd OPEN Note If the data set is already open no operation is performed for OPEN e FINIS To close the data set after writing to it Closing the data set allows other execs to access it and its ddname When you specify FINIS it forces the completion of all I O operations by physically writing the contents of any parti
31. you could write the following instructions Note the MOD attribute on the second allocation which appends the 5 lines at the end of the data set rather than on top of existing data r Appending 5 Lines of Data to an Existing Data Set ALLOC DA weekly input mar28 F myindd SHR REUSE ALLOC DA yearly output F myoutdd MOD EXECIO 5 DISKR myindd FINIS EXECIO 5 DISKW myoutdd FINIS Note Do not use the MOD attribute when allocating a member of a PDS to which you want to append information You can use MOD only when appending information to a sequential data set To append information to a member of a PDS rewrite the member with the additional records added Chapter 12 Processing Data and Input Output Processing 12 9 Using EXECIO to Process Information Copying Information to and from a List of Compound Variables When copying information from a data set you can store the information in the data stack which is the default or you can store the information in a list of compound variables Similarly when copying information back to a data set you can remove information from the data stack which is the default or you can remove the information from a list of compound variables Copying Information from a Data Set to a List of Compound Variables To copy an entire data set into compound variables with the stem newvar and then display the list write the following instructions Copying an Entire D
32. 1 What is a Data Stack lol ln 11 1 Manipulating the Data Stack 0 0 00 0000000 11 2 Processing of the Data Stack 200 0000 4 11 5 Using the Data Stack olo les 11 6 Creating a Buffer on the Data Stack 2 0 11 9 Creating a Buffer with the MAKEBUF Command 11 10 Dropping a Buffer with the DROPBUF Command 11 10 Finding the Number of Buffers with the QBUF Command 11 11 Finding the Number of Elements In a Buffer i n 11 11 Protecting Elements in the Data Stack 11 14 Contents V Creating a New Data Stack with the NEWSTACK Command 11 15 Deleting a Private Stack with the DELSTACK Command 11 16 Finding the Number of Stacks 0004 11 16 Chapter 12 Processing Data and Input Output Processing 12 1 Types of Processing len 12 1 Dynamic Modification of a Single REXX Expression 12 2 Using the INTERPRET Instruction 12 2 Using EXECIO to Process Information to and from Data Sets 12 2 When to Use the EXECIO Command 12 2 Using the EXECIO Command 00 0000004 12 3 Return Codes from EXECIO 2 2 0 0 ln 12 7 When to Use the EXECIO Command 12 8 Chapter 13 Using REXX in TSO E and Other MVS Address Spaces 13 1 Services Available to REXX E
33. 12 6 data stack adding an element 11 2 characteristic 11 6 creating a buffer 11 9 creating a new stack 11 15 deleting a private stack 11 16 description 11 1 determining the number of elements on the stack 11 3 dropping one or more buffers 11 10 finding the number of buffers 11 11 finding the number of elements in 11 11 finding the number of stacks 11 16 manipulating 11 2 passing information between an exec and a routine 11 6 passing information to an interactive command 11 8 protecting an element 11 14 removing an element 11 3 removing an element from a stack with a buffer 11 10 search order for processing 11 5 type of input 11 5 using in MVS batch 13 10 using in TSO E background 13 10 DATATYPE built in function 5 8 DBCS ddname See also system file allocating to for VO 12 4 12 7 use in EXECIO command 12 4 12 7 debug for error 9 1 interactive debug facility 9 4 with REXX special variable 9 3 DELSTACK command 11 16 diagnosis problem within an exec 9 1 DO FOREVER loop 4 11 DO UNTIL loop flowchart 4 16 DO WHILE loop flowchart 4 14 DO END instruction 4 8 double byte character set names in execs 2 9 DROPBUF command 11 10 E edit an exec A 7 environment defining in REXX 13 12 host command 8 6 language processor 13 12 error debugging 3 14 9 1 tracing command 9 2 tracing expression 3 14 error message getting more information 2 14 interpreting 2 13 syntax error 2 13 example use of uppercase and lowercase xiv exclus
34. 1975 Passing Information by Using Arguments A way to pass information to either internal or external subroutines is through arguments You can pass up to 20 arguments separated by commas on the CALL instruction as follows CALL subroutine name argumentl argument2 argument3 Using the ARG Instruction The subroutine can receive the arguments with the ARG instruction Arguments are also separated by commas in the ARG instruction ARG argl arg2 arg3 The names of the arguments on the CALL and the ARG instructions do not have to be the same because information is not passed by argument name but by position The first argument sent becomes the first argument received and so forth You can 6 6 05 390 V1R2 0 TSO E REXX User s Guide Writing a Subroutine also set up a template in the CALL instruction which is then used in the corresponding ARG instruction For information about parsing with templates see Parsing Data on page 7 4 The following exec sends information to an internal subroutine that computes the perimeter of a rectangle The subroutine returns a value in the variable perim that is specified after the RETURN instruction The main exec receives the value in the special variable RESULT Example of Passing Arguments on the CALL Instruction JDEESIEESOUE SOEUR GO SRA eee eee REXX rai deere QUUD EROR Ae greene te This exec receives as arguments the length and width of a rectangl
35. 390 V1R2 0 TSO E REXX User s Guide Using Conditional Instructions When you put the entire instruction on one line you must separate the THEN clause from the ELSE clause with a semi colon IF expression THEN instruction ELSE instruction Generally at least one instruction should follow the THEN and ELSE clauses When either clause has no instructions it is good programming practice to include NOP no operation next to the clause IF expression THEN instruction ELSE NOP If you have more than one instruction for a condition begin the set of instructions with a DO and end them with an END IF weather rainy THEN SAY Find a good book ELSE DO SAY Would you like to play tennis or golf PULL answer END Without the enclosing DO and END the language processor assumes only one instruction for the ELSE clause Nested IF THEN ELSE Instructions Sometimes it is necessary to have one or more IF THEN ELSE instructions within other IF THEN ELSE instructions Having one type of instruction within another is called nesting With nested IF instructions it is important to match each IF with an ELSE and each DO with an END IF weather fine THEN DO SAY What a lovely day IF tenniscourt free THEN SAY Shall we play tennis ELSE NOP END ELSE SAY Shall we take our raincoats Not matching nested IFs to ELSEs and DOs to ENDs can have some surprising results If you eliminate the DOs and ENDs and the ELSE NOP as in the
36. 5 RETURN Chapter 6 Writing Subroutines and Functions 6 5 Writing a Subroutine r Example Without the PROCEDURE Instruction kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX K RRR RR RR kkk k kkk kkk kkk RR ERE kk This exec does not use a PROCEDURE instruction to protect the variables within its subroutine x RR RI RRR RRR REE kek e k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk numberl 10 CALL subroutine SAY numberl number2 displays 7 5 EXIT subroutine numberl 7 number2 5 RETURN Exposing Variables with PROCEDURE EXPOSE To protect all but specific variables use the EXPOSE option with the PROCEDURE instruction followed by the variables that are to remain exposed to the subroutine r Example Using PROCEDURE EXPOSE RR kkk kk EER RRR ERR RR ER IKREREARER REXX kkk RRR KKK KER k k k kk RRR ER ERR This exec uses a PROCEDURE instruction with the EXPOSE option tox expose one variable numberl in its subroutine The other variable number2 is set to null and displays its name in uppercase x RR RR RRR RRR RRR ERR KR ERIK KERIKERI AKER AKER AK KKK IK KKK EK KKK kk kkk k kk ERE numberl 10 CALL subroutine SAY numberl number2 displays 7 NUMBER2 EXIT subroutine PROCEDURE EXPOSE number1 numberl 7 number2 5 RETURN For more information about the PROCEDURE instruction see TSO E REXX Reference SC28
37. 7 B amp B lt 3 A B C THEN Like the priority of operators within the arithmetic operators there is an overall priority that includes all operators The priority of operators is as follows with the highest first 3 12 0S 390 V1R2 0 TSO E REXX User s Guide Using Expressions r Overall Operator Priority Vor Prefix operators s Power exponential 96 ll Multiply and divide Add and subtract blank abuttal Concatenation operators gt lt etc Comparison operators amp Logical AND amp amp Inclusive OR and exclusive OR Thus the previous example presented again below IF A gt 7 B amp B lt 3 A B C THEN given the following values A 8 B 2 C 10 would be evaluated as follows 1 Convert variables to values IF 8 gt 7 2 amp 2 lt 3 8 2 10 THEN 2 Compute operations of higher priority within parentheses e Exponential operation IF 8 gt 7 2 amp 2 lt 3 8 2 10 THEN 49 e Concatenation operation IF 8 gt 49 amp 2 lt 3 8 2 10 THEN 82 3 Compute all operations within parentheses from left to right IF 8 gt 49 amp 2 lt 3 82 10 THEN Mu Nc af 0 1 0 4 Logical AND 0 amp 1 0 0 5 Inclusive OR 0 0 Chapter 3 Using Variables and Expressions 3 13 Tracing Expressions with the TRACE Instruction Exercises Priority of Operators 1 What
38. Co ll lt KR ll quote Experience is the best teacher quote Experience is the best teacher PARSE VAR quote 1 v1 11 v2 6 v3 4 v4 o m Rr RON o lt lt lt lt Q first 7 quote Experience is the best teacher PARSE VAR quote 1 v1 first v2 6 v3 a vi b v2 c v3 7 10 09 390 V1R2 0 TSO E REXX User s Guide Parsing Data quotel Knowledge is power quote2 Ignorance is bliss quote3 Experience is the best teacher CALL subl quotel quote2 quote3 EXIT subl PARSE ARG wordl word2 word3 a word1 b word2 C word3 ANSWERS 1 a word1 Experience b word2 is c word3 the best teacher a word1 Experience b word2 is c word3 the d word4 best e word5 teacher f word6 a word1 Experience b word2 is c word3 teacher g lt A I Expe rience is the best teacher X lt m l v1 Experience v2 S v3 the best teacher v4 perience is the best teacher a v1 THE BEST TEACHER b v2 IS c v3 EXPERIENCE v1 Experience v2 is the v3 best teacher a b C d v4 the best teacher Chapter 7 Manipulating Data 7 11 Parsing Data 8 a v1 Experi b v2 ence C v3 s the best teacher 9 a word1 Knowledge b word2 Ignorance c word3 Experience 7 12 0S 390 V1R2 0 TSO E REXX User s Guide
39. Copying Information from a Data Set to a List of Compound Variables x eere a Dee e Ree EQ obser as d 12 10 Copying Information from Compound Variables to a Data Set 12 10 Updating Information in a Data Set 12 10 Updating a single line c lllnn 12 11 Updating multiple lines llis 12 11 Additional Examples soo c eose casa rad tui rrenda ees 12 13 This chapter describes dynamic modification of a single REXX expression and I O processing of data sets Types of Processing The word processing is used here to mean the performance of operations and calculations on data Normal processing of instructions in REXX occurs every time the language processor evaluates an expression This chapter describes two special types of REXX processing e Dynamic modification of a single REXX expression The INTERPRET instruction evaluates an expression and then treats it as a REXX instruction e Processing information to and from data sets The TSO E REXX EXECIO command in an exec reads information from a data set to the data stack or a list of variables and writes information from the data stack or list of variables back to a data set Copyright IBM Corp 1988 1996 12 1 Using EXECIO to Process Information Dynamic Modification of a Single REXX Expression Typically REXX expressions are evaluated and the result replaces the expression For example the arithmetic
40. E REXX User s Guide SAY employee 5 SAY employee 10 SAY employee oldest employee new Clark Evans SAY employee new Using Compound Variables and Stems Displays Nobody Displays Nobody Displays Nobody Displays Clark Evans You can use stems with the EXECIO command when reading to and writing from a data set For information about the EXECIO command see Using EXECIO to Process Information to and from Data Sets on page 12 2 You can also use stems with the OUTTRAP external function when trapping command output For information about OUTTRAP see Using the OUTTRAP Function on page 10 6 Exercises Using Compound Variables and Stems 1 After these assignment instructions what is displayed in the following SAY instructions assigns 3 to variable A 4 to B x last to C x 2 to A 4 5 to A last cv3d to X 3 4 2 After these assignment instructions what is displayed a 3 b 4 c last a b 2 a c 5 x a b cv3d a SAYa b SAYB c SAYc d SAY aa e SAY AB f SAY b c g SAY c a h SAY a first i SAY x a 4 hole 1 full hole empty hole s full a SAY hole 1 b SAY hole s c SAY hole mouse ANSWERS a b c last d A 3 e f B last Chapter 7 Manipulating Data 7 3 Parsing Data C 3 A FIRST i cv3d 2o a empty full c empty o Parsing Data Parsing in REXX is separatin
41. ELSE EDIT dsname use TSO E line mode edit Examples Using the ADDRESS Instruction r ADDRESS Example 1 Ek kk k k k kkk dek k k kk k k k k kk k k k k kk k k REXX KK k k A A K A K k k kk k k k k Kk K K k k kk kkk is exec mus e run in E asks users i ey know the Th tb ISPF It ask f they k the eys and when e answer is a variation o no i isplays PF k d when th t f no td the panel with the PF key definitions EK kk k k k e kek e ke k k kek k k k e kk de ke k k kk k k k k k k k k k k kk k k k k kk k k k k kk k k k k kk k kk k kkk kk SAY Do you know your PF keys PULL answer IF answer NO answer N THEN ADDRESS ispexec display PANEL ispopt3c ELSE SAY 0 K Never mind m ADDRESS Example 2 RR kk RRR EER RR EER RRR ERK k EER kk k k REXX KR KKK KIRKE KKK RE KKK RARER ERE RE This exec must be run in ISPF It blanks out previous data set name information from the fields of an ISPF panel named newtool It then displays the panel to the user RR RR RRR RRR REE RRR ERIK REI kk k k k e kk e k k k kk k k k KKK IK KIKI A KKK kk KKK k ERR ADDRESS ispexec CALL blankem Call an internal subroutine IF RC 0 THEN display PANEL newtool ELSE setmsg MSG nt001 Send an error message EXIT blankem vget ZUSER ntgroup nttype ntmem RETURN RC 8 12 05 390 V1R2 0 TSO E REXX User s Guide
42. Functions To prevent the display of TSO E messages as an exec runs use the MSG function followed by the word OFF enclosed within parentheses status MSG OFF status is set to the previous setting of MSG and sets the current setting to OFF To resume the display of TSO E messages substitute the word ON for OFF To find out if messages will be displayed issue the MSG function followed by empty parentheses status MSG status is set to ON or OFF Using the MVSVAR Function The MVSVAR function retrieves information about MVS TSO E and the current session such as the symbolic name of the MVS system or the security label of the TSO E session The information retrieved depends on the argument specified To retrieve the information use the MVSVAR function immediately followed by an argument value enclosed in parentheses For example to find out the APPC MVS logical unit LU name use the MVSVAR function with the argument SYSAPPCLU appclu MVSVAR SYSAPPCLU The MVSVAR function is available in any MVS address space Compare this to the SYSVAR function which also retrieves system information but can only be used in REXX execs that run in the TSO E address space Many of the MVSVAR arguments retrieve the same information as do CLIST control variables The following table lists the items of information that are available for retrieval by MVSVAR Argument Value Descrip
43. Host command environments TSO E REXX has the ability to invoke commands from several environments in MVS and ISPF as well as from TSO E The ADDRESS instruction sets the environment for commands For more information see Issuing Other Types of Commands from an Exec on page 8 6 Parsing capabilities For separating data into variable names and formatting text REXX provides extensive parsing through templates For more information see Parsing Data on page 7 4 Use of a data stack REXX offers the use of a data stack in which to store data For more information see Chapter 11 Storing Information in the Data Stack on page 11 1 Use of mixed and lowercase characters Although variables and most input are translated to uppercase REXX provides ways to maintain mixed and lowercase representation For more information see Preventing Translation to Uppercase on page 2 14 In some ways CLIST and REXX are similar The following tables show similarities and differences in the areas of Copyright IBM Corp 1988 1996 Accessing system services e Controlling program flow Debugging Execution Interactive communication Passing information e Performing file I O e Syntax Using functions Using variables C 1 Accessing System Information CLIST REXX LISTDSI statement LISTDSI amp BASEDS LISTDSI external function x LISTDSI baseds amp SYSOUTTRAP and amp SYSOUTLINE SET SYSOUT
44. Infinite Loops What happens when the control variable of a loop cannot attain the last number For example in the following exec segment count does not increase beyond 1 DO count 1 to 10 SAY Number count count count 1 END The result is called an infinite loop because count alternates between 1 and 0 and an endless number of lines saying Number 1 appear on the screen r IMPORTANT Stopping An Infinite Loop When you suspect an exec is in an infinite loop you can end the exec by pressing the attention interrupt key sometimes labeled PA1 You will then see message IRX0920I In response to this message type HI for halt interpretation and press the Enter key If that doesn t stop the loop you can press the attention interrupt key again type HE for halt execution and press the Enter key HI will not halt an infinitely looping or long running external function subroutine or host command written in a language other than REXX and that was called by your exec The HI condition is not checked by the REXX interpreter until control returns from the function subroutine or host command r Example of EXEC1 an exec that calls an external function EK kk k k k kkk kk k kk kk kkk REX KX RRR RRR RRR RR RARER RAK RE KKK RARER ERE RE Invoke a user written external function myfunct x not written in REXX For example it might have been coded x in PL I or assembler x RR kk RRR RRR REE R RR e RIKKI
45. Input Try various input and observe the output Now change the PULL instruction to a PARSE PULL instruction and observe the difference Passing Information to an Exec When an exec runs you can pass information to it in several ways two of which are Through terminal interaction By specifying input when invoking the exec Using Terminal Interaction The PULL instruction is one way for an exec to receive input as shown by a previous example repeated here r Example of an Exec that Uses PULL EK kk k k k kekek deke k k kk k k k kkk kk k k kk REXX KR KK KKK KKK kA k k k k Kk k K K k kk k k kk kkk kk This exec adds two numbers and displays their sum E kk k k e e ek e ke e k kk k k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k kkk kkk k kkk kk SAY Please enter a number PULL number1 SAY Now enter a number to add to the first number PULL number2 sum numberl number2 SAY The sum of the two numbers is sum The PULL instruction can extract more than one value at a time from the terminal by separating a line of input as shown in the following variation of the previous example r Variation of an Example that Uses PULL kkkkkkkkkkkkkkkkkkkkkkkkkkxkxk REX X RRR RR kk RRR RIK RRR k k k kkk kkk k ERE kk This exec adds two numbers and displays their sum x RR RRR RRR kk deje eee dek KEI kk k k k e kk k k k K KEI k KKK IAAI KKK k ERR SAY Please enter two
46. KERIKERI KERIB KKK IA k k kk k k k k kk KKK ERR x myfunct 1 exit If myfunct enters an infinite loop pressing the attention interrupt key and entering HI will not stop myfunct However pressing the attention interrupt key and then entering HE will stop the function and the exec EXEC1 that called it HE does not automatically stop any exec that called EXEC1 unless you are running under ISPF For more information about the HE condition see TSO E REXX Reference SC28 1975 Note HE does not alter the halt condition which is raised by HI If you entered HI before you entered HE for example you may have first issued HI and it failed to 4 10 05 390 V1R2 0 TSO E REXX User s Guide Using Looping Instructions end your exec the halt condition will remain set for the exec and all calling execs HE will stop your exec and then the halt condition raised when you entered HI will be recognized by any exec that called your exec DO FOREVER Loops Sometimes you might want to purposely write an infinite loop for instance in an exec that reads records from a data set until it reaches end of file or in an exec that interacts with a user until the user enters a particular symbol to end the loop You can use the EXIT instruction to end an infinite loop when a condition is met as in the following example More about the EXIT instruction appears in EXIT Instruction on page 4 20 Example Using a DO FOREVER Loop k
47. OS 390 V1R2 0 TSO E REXX User s Guide Using Looping Instructions When you run this example you see five lines of Hello Hello Hello Hello Hello Hello You can also use a variable in place of a constant as in the following example which gives you the same results number 5 DO number SAY Hello END A variable that controls the number of times a loop repeats is called a control variable Unless you specify otherwise the control variable increases by 1 each time the loop repeats DO number 1 TO 5 SAY Loop number SAY Hello END SAY Dropped out of the loop when number reached number This example results in five lines of He11o preceded by the number of the loop The number increases at the bottom of the loop and is tested at the top Je Loop 1 Hello Loop 2 Hello Loop 3 Hello Loop 4 Hello Loop 5 Hello Dropped out of the loop when number reached 6 You can change the increment of the control variable with the keyword BY as follows DO number 1 TO 10 BY 2 SAY Loop number SAY Hello END SAY Dropped out of the loop when number reached number This example has results similar to the previous example except the loops are numbered in increments of two Chapter 4 Controlling the Flow Within an Exec 4 9 Using Looping Instructions Loop 1 Hello Loop 3 Hello Loop 5 Hello Loop 7 Hello Loop 9 Hello Dropped out of the loop when number reached 11
48. Other Types of Commands from an Exec 8 14 05 390 V1R2 0 TSO E REXX User s Guide Debugging Execs Chapter 9 Diagnosing Problems Within an Exec Debugging Execs lt pt oa piaga a a rss 9 1 Tracing Commands with the TRACE Instruction 9 2 TRACE G 2 p aaa aar A i St Ae OEE Roo eee a ie a 9 2 ERACE E uuo ede Taa e o a E E A AA SES A 9 2 Using REXX Special Variables RC and SIGL 9 3 RES hve oar i aE Gee Ao ee Len Rb Ds s dh EAE E N catus re de qa te 9 3 SIG leue we Sad PEE Le we hU ee aS oe 9 3 Tracing with the Interactive Debug Facility 9 4 Starting Interactive Tracing 2 llle 9 4 Option of the TRACE Instruction lll 9 4 EXECUTIL TS Command sls 9 5 Options Within Interactive Trace loose 9 7 Continuing Interactive Tracing llle 9 7 Typing Additional Instructions to be Processed 9 7 Re executing the Last Instruction Traced 2 9 7 Ending Interactive Trace ss 9 8 TBAGE OEFE Libet meu ex Re Ae qi s 9 8 Endthe Exec a oei p Gaon aa llle 9 8 TBAGE 2 nto As BAe oe a Nee bE OIE CURA he SE a 9 8 PXECUTIL TE 24 un suene kyo oS e Sea eee a ae RE Ye 9 8 This chapter describes how to trace command output and other debugging techniques Debugging Execs When you encounter an error in an exec there are several ways to locate the error The TRACE instruction displays how the language
49. PULL or ARG instruction ARG numberl number2 The period acts as a dummy variable to collect unwanted extra information If there is no extra information the period is ignored You can also use a period as a place holder within the PULL or ARG instruction as follows ARG numberl number2 In this case the first value 42 is discarded and number1 and number2 get the next two values 21 and 10 Preventing Translation of Input to Uppercase Like the PULL instruction the ARG instruction changes alphabetic characters to uppercase To prevent translation to uppercase precede ARG with PARSE as demonstrated in the following example r Example of an Exec that Uses PARSE ARG RR kkk kkk kkk RRR kkk kk kkk kkk kkk REX XK RRR RRR RR KKK KKK KERR k k kk RRR ERE RR This exec receives the last name first name and score of a student and displays a sentence reporting the name and x Score x RR RR RRR RRR REE RRR ERIK KERIKERI KERRI ERIK KEI k KKK IA k k k RIKER ERE PARSE ARG lastname firstname score SAY firstname lastname received a score of score Exercises Using the ARG Instruction The left column shows the input values sent to an exec The right column is the ARG statement within the exec that receives the input What value does each variable assume Input Variables Receiving Input 1 115 23 66 5 8 ARG first second third 2 2 0 569 2E6 ARG first second third fourth 3 13 13 13 13 ARG fir
50. Part 2 PART Il Using REXX In addition to being a versatile general purpose programming language REXX can interact with TSO E MVS APPC MVS and ISPF which expands its capabilities This part of the book is for programmers already familiar with the REXX language and experienced in TSO E The chapters in this part cover the following topics e Chapter 8 Entering Commands from an Exec on page 8 1 A REXX exec can issue different types of host commands within the same exec Chapter 9 Diagnosing Problems Within an Exec on page 9 1 Several debugging options are available in an exec Chapter 10 Using TSO E External Functions on page 10 1 TSO E external functions are provided to interact with the system to do specific tasks e Chapter 11 Storing Information in the Data Stack on page 11 1 The data stack is useful in I O and other types of special processing Chapter 12 Processing Data and Input Output Processing on page 12 1 You can process information to and from data sets by using the EXECIO command Chapter 13 Using REXX in TSO E and Other MVS Address Spaces on page 13 1 You can run execs in other MVS address spaces besides TSO E foreground and background Note Although you can write a REXX exec to run in a non TSO E address space in MVS the chapters and examples in this part unless otherwise stated assume the exec will run in a TSO E address space If you want to write execs that
51. Prepare To Receive Type e CMSRC Set Return Control e CMSRT Set Receive Type CMSSL Set Sync Level e CMSST Set Send Type e CMSTPN Set TP Name e CMTRTS Test Request To Send Received ai iam _ p e The SAA CPI Communications calls are described in SAA Common Programming Interface Communications Reference The following APPC MVS calls are supported under the LU62 host command environment ATBALC2 Allocate ATBALLC Allocate e ATBCFM Confirm e ATBCFMD Confirmed ATBDEAL Deallocate ATBFLUS Flush ATBGETA Get Attributes e ATBGETO Get Conversation ATBGETP Get TP Properties ATBGETT Get Type ATBGTA2 Get Attribute ATBPTR Prepare To Receive ATBRCVI Receive Immediate e ATBRCVW Receive And Wait Chapter 8 Entering Commands from an Exec 8 9 Issuing Other Types of Commands from an Exec e ATBRTS Request_To_Send ATBSEND Send Data e ATBSERR Send Error Note The numeric suffix within the service name indicates the MVS release in which the service was introduced and thereby also available in all subsequent releases as follows none MVS SP4 2 service For example ATBGETA 1 MVS SP4 2 2 service For example ATBTEA1 2 MVS SP4 3 service For example ATBALC2 Therefore your OS 390 base control program BCP must be at least at the indicated level to take advantage of these services The parameters for these services
52. QUEUE instructions to put T S 0 E on the data stack EK kk k k k e ek e ke k e kek k k k e kk de ke k k kk RIKER AK EKA k k kk k k k k kk k k k k kk k kk k kk k kk PUSH S J esekekeekekeekekedekekedekekekekekekcekejeekee QUEUE 0 Data in stack is x PUSH T second push T x QUEUE E first push S x first queue 0 DO QUEUED second queue E PULL stackitem VERETETT EEEE EEEE EE E SAY stackitem END 11 4 09 390 V1R2 0 TSO E REXX User s Guide Processing of the Data Stack Processing of the Data Stack You can think of a data stack as a temporary holding place for information Every TSO E REXX user has a separate data stack available for each REXX environment that is initialized REXX environments are initialized at the READY prompt when you enter ISPF and again when you split the screen in ISPF When an exec issues a PULL instruction and when it issues an interactive TSO E command the data stack is searched first for information and if that is empty information is retrieved from the terminal Data Stack Terminal Some types of input that can be stored on the data stack are e Data for the PULL and PARSE PULL instructions When an exec issues a PULL instruction the language processor first goes to the data stack and pulls off the top element If the data stack is empty the language processor goes to the terminal for input When the data stack is empty the PULL i
53. SYSDSN 10 9 SYSVAR 10 10 using EXIT 6 11 using PROCEDURE 6 13 using PROCEDURE EXPOSE 6 14 using RETURN 6 11 when to make internal or external 6 12 function continued writing 6 11 function package description 10 17 local 10 17 system 10 17 user 10 17 G GETMSG external function 10 1 10 2 GOTO See SIGNAL instruction H HE halt execution 4 10 HI halt interpretation 4 10 host command environment APPC MVS 8 8 changing 8 11 checking if it is available 8 11 compared to language processor environment 13 12 default 8 6 8 8 description 8 6 finding the active environment 8 11 IBM Compiler for REXX 370 benefits 1 3 IBM Library for REXX 370 benefits 1 3 identifier of anexec 2 2 2 8 13 4 IF THEN ELSE instruction flowchart 4 2 matching clauses 4 3 nested 4 3 using DO and END 4 3 using NOP 4 3 IKJEFTO1 13 7 implicit execution 2 12 A 1 from ISPF PDF command line 2 12 from ISPF PDF command option 2 12 from READY 2 12 speeding up search time 2 13 using 2 13 inclusive OR 3 10 infinite loop from TSO E background and MVS batch 13 10 stopping 4 10 input passing argument 2 19 preventing translation to uppercase 2 18 input continued receiving with ARG 2 17 receiving with PULL 2 16 sending with EXEC command 2 17 to an exec preventing translation to uppercase 2 15 2 18 using a period as a place holder 2 18 input output I O allocating a ddname 12 4 12 7 reading from a data set 12 3 reading to compound var
54. Solution kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX XK kkk kkk k kkk kkk kkk kkk kkk kk This exec uses a DO WHILE loop to keep track of window seats in an 8 seat comuter airline K kk k k k e ke e e e e kek e k k e kek de ke k k kk k k k k RRR IK ERIK k kk k k k k kk k k k k kk k kk k kk k kk window_seats 0 Initialize window seats to 0 x passenger 0 Initialize passengers to 0 DO WHILE passenger lt 8 amp window seats 4 BRR k RRR A KKK e RRR RIK RRR ER KKK EKER IKK IKK IARI KEI IKKE ER Continue while you have not questioned all 8 passengers and while all the window seats are not taken x BRK k RRR ARR REA KR RRA RRR EA KKK ERIK ERIK KR KIKI kk k k k AKER k k k kk kkk SAY Do you want a window seat Please answer Y or N PULL answer passenger passenger 1 Increase the number of passengers by 1 IF answer Y THEN window seats window seats 1 Increase the number of window seats by 1 ELSE NOP END SAY window seats window seats were assigned SAY passenger passengers were questioned Chapter 4 Controlling the Flow Within an Exec 4 15 Using Looping Instructions DO UNTIL Loops DO UNTIL loops in a flowchart appear as follows pounTiL Y A gt instruction s Fal expression True END As REXX instructions the flowchart example looks like DO UNTIL expression expression must be false instruction s END Use DO UNTIL loops when a
55. The label to which control passes can appear before or after the SIGNAL instruction Unlike CALL SIGNAL does not return to a specific instruction to resume execution When you use SIGNAL from within a loop the loop automatically ends and when you use SIGNAL from an internal routine the internal routine will not return to its caller In the following example if the expression is true then the language processor goes to the label Emergency and skips all instructions in between IF expression THEN SIGNAL Emergency 4 ELSE instruction s Y Emergency instruction s SIGNAL is useful for testing execs or to provide an emergency course of action It should not be used as a convenient way to move from one place in an exec to another SIGNAL does not provide a way to return as does the CALL instruction described in CALL RETURN Instructions on page 4 21 For more information about the SIGNAL instruction see page 9 3 and TSO E REXX Reference SC28 1975 4 22 OS 390 V1R2 0 TSO E REXX User s Guide Chapter 5 Using Functions What is a Function 0000000 ee ee 5 1 Example ofa Function 0 0 0 00 eee ee A 5 3 Built In Functions s npe meet Ree ee ee eor m eg 5 4 Arithmetic Functions ss 5 4 Comparison Functions 0 00020 pee ee 5 5 Conversion Functions 22s 5 5 Formatting Functions 2 teda eaa he ile ana a ba a 5 5 String Manipulating Functions aaaea a 5 6 Miscellan
56. WITH 7 5 PARSE VAR 7 5 PULL 7 4 multiple strings 7 9 separator blank 7 6 number 7 7 string 7 6 variable 7 6 template 7 6 partitioned data set creating in ISPF PDF A 5 creating with ALLOCATE A 9 description A 1 for an exec 2 1 passing arguments 2 19 PDS See partitioned data set period as place holder 2 18 portability of compiled REXX programs 1 4 prefix in a data set name 2 1 8 2 preliminary checklist A 3 PROCEDURE instruction 6 5 6 6 6 13 6 14 Procedures Language xiii prompt from TSO E command 8 4 10 7 overridden by an item in the data stack 11 14 overridden by item in the data stack 8 4 overridden by NOPROMPT in the PROFILE 8 4 10 7 PROMPT external function 10 7 PROMPT function 8 4 11 16 protection of an element on a data stack 11 14 PULL instruction 2 16 7 4 11 3 PUSH instruction 11 2 Q QBUF command 11 11 QELEM command 11 11 Index X 7 QSTACK command 11 16 queue description 11 1 FIFO order 11 1 QUEUE instruction 11 2 QUEUED built in function 11 3 11 10 quotation mark 8 2 around a literal string 2 3 around command 2 15 8 2 in an instruction 2 3 to prevent translation to uppercase 2 15 R RC special variable for debugging 9 3 used with a command 8 1 used with stack command 11 11 11 16 repetitive loop 4 8 RESULT special variable 6 7 6 8 8 5 used with EXIT 4 20 REXX compiler benefits 1 3 REXX environment definition 13 12 REXX exec identifier 2 2 2 8 13 4 REXX instruction adding during
57. Writing a Subroutine 2s 6 3 Passing Information to a Subroutine sr 6 4 Passing Information by Using Variables 6 4 Protecting Variables with the PROCEDURE Instruction 6 5 Exposing Variables with PROCEDURE EXPOSE 6 6 Passing Information by Using Arguments 6 6 Using the ARG Instruction aaa 6 6 Using the ARG Built in Function oos 6 7 Receiving Information from a Subroutine 6 8 Example Writing an Internal and an External Subroutine 6 8 Writing a Function usse monk RR x bm Ru eee ed EE d 6 11 Passing Information to a Function 0 6 12 Passing Information by Using Variables 6 12 Protecting Variables with the PROCEDURE Instruction 6 13 Exposing Variables with PROCEDURE EXPOSE 6 14 Passing Information by Using Arguments 6 15 Using the ARG Instruction aa 6 15 Using the ARG Built in Function 6 16 Receiving Information from a Function 04 6 16 Exercise Writing a Function 00000004 6 17 Summary of Subroutines and Functions 4 6 18 This chapter shows how to write subroutines and functions and compares their differences and similarities What are Subroutines and Functions Subroutines and functions are routines made up of a sequence o
58. a REXX exec identifier appears later on page 2 8 When you run the exec you see on your screen the sentence This is a REXX exec Even in a longer exec the instructions flow like ordinary English and are easy to understand r Example of a Longer Exec kkkkkkkkkkkkkk kkk kkkkkkkkkkxk REX XK RRR RRR kk kkk kkk RRR k k k k kk RRR ERE RE This exec adds two numbers and displays their sum EK kk k k e e ek e ke k e kek k k k e kk de k k k kk k k k e kk k k k k kk k k k KKK k k k k kk k k k k kk k kk k kkk kk SAY Please enter a number PULL number1 SAY Now enter a number to add to the first number PULL number2 sum numberl number2 SAY The sum of the two numbers is sum 2 2 OS 390 V1R2 0 TSO E REXX User s Guide Syntax of REXX Instructions When you run the example the exec interacts with you at the terminal First you see on your screen Please enter a number When you type a number for example 42 and press the Enter key the variable number1 is assigned the value 42 You then see another sentence on the screen Now enter a number to add to the first number When you enter another number for example 21 the variable number2 is assigned the value 21 Then the values in numberl1 and number2 are added and the total is assigned to sum You see a final sentence on the screen displaying the sum The sum of the two numbers is 63 Before you actually try these example
59. an exec from READY mode and from an ISPF panel Chapter 9 Diagnosing Problems Within an Exec 9 5 Debugging Execs e From Within an Exec You can issue the EXECUTIL TS command from within an exec EXECUTIL TS EXIT The exec is then interactively traced from the point in the exec at which the command was issued Any other execs that the exec invokes are also interactively traced You can also issue EXECUTIL TS from within a CLIST to initiate tracing in execs that the CLIST invokes From READY Mode You can issue the command from READY mode READY executil ts The next exec invoked from READY mode is then interactively traced If that exec invokes another exec the invoked exec is also interactively traced From an ISPF Panel You can also issue EXECUTIL TS from the ISPF COMMAND option or from the command line of an ISPF panel TSO COMMAND PROCESSOR ENTER TSO COMMAND OR CLIST BELOW gt executil ts COMMAND gt tso executil ts The next exec invoked from ISPF is then interactively traced If that exec calls another exec the called exec is also interactively traced If you are in split screen mode in ISPF an exec run from the opposite screen is not interactively traced because each side of a split screen is a different environment To begin interactive trace after pressing the attention interrupt key sometimes labeled PA1 enter TS trace start after the
60. and the requirements for using them in APPC MVS transaction programs are described in OS 390 MVS Writing TPs for APPC MVS GC28 1775 Examples Using APPC MVS Services The following example illustrates the syntax for invoking an SAA CPI Communications call under the CPICOMM host command environment r CPICOMM Example REXX ADDRESS CPICOMM CMALLC conversation id return_code if return code CM OK then say OK else say Why not The following example illustrates the syntax for invoking an APPC MVS call under the LU62 host command environment m LU62 Example REXX ADDRESS LU62 ATBDEAL conversation id deallocate type notify type return_code Whenever you issue an SAA CPI Communications call or APPC MVS call from a REXX program the entire call must be enclosed in single or double quotes SAA CPI Communications calls and APPC MVS calls can use pseudonyms rather than integer values In the CPICOMM example instead of comparing the variable return code to an integer value of 0 the example compares return code to the pseudonym value CM OK The integer value for CM OK is 0 TSO E provides two pseudonym files one for the LU62 host command environment and one for the CPICOMM host command environment These files define the pseudonyms and their integer values The LU62 pseudonym file is REXAPPC1 and the CPICOMM pseudonym file is REXAPPC2 Both files are found in SYS1 SAMPLIB You can inclu
61. are no more data sets enter QUIT PULL dataset_name IF dataset name QUIT THEN LEAVE ELSE DO PRINTDS DA dataset name SAY dataset name printed END END SAY Good bye ITERATE Instruction Another instruction ITERATE stops execution from within the loop and passes control to the DO instruction at the top of the loop Depending on the type of DO instruction a control variable is increased and tested and or a condition is tested to determine whether to repeat the loop Like LEAVE ITERATE is used within the loop DO count 1 TO 10 IF count 8 THEN ITERATE ELSE SAY Number count END This example results in a list of numbers from 1 to 10 with the exception of number 8 Number Number Number Number Number Number Number Number Number L2 40 oO0014C00n9 7 4 12 09 390 V1R2 0 TSO E REXX User s Guide Using Looping Instructions Exercises Using Loops 1 What are the results of the following loops a DO digit 1 TO 3 SAY digit END SAY Digit is now digit b DO count 10 BY 2 TO 6 SAY count END SAY Count is now count C DO index 10 TO 8 SAY Hup Hup Hup END SAY Index is now index 2 Sometimes an infinite loop can occur when input to end the loop doesn t match what is expected For instance in the previous example using the LEAVE Instruction on page 4 12 what happens when the user enters Quit and the PULL instruction is changed to a PARSE PULL i
62. condition is not true and you want to execute the loop until the condition is true The DO UNTIL loop tests the condition at the end of the loop and repeats only when the condition is false Otherwise the loop executes once and ends For example r Example Using DO UNTIL kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX XK RRR RRR kkk kkk kkk kkk kkk kkk kk This exec uses a DO UNTIL loop to ask for a password If the password is incorrect three times the loop ends RRRR RRR EERE ERR ke k ERIK e ke k k kk k k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k kk k kkk kk password abracadabra time 0 DO UNTIL answer password time 3 SAY What is the password PULL answer time time 1 END 4 16 09 390 V1R2 0 TSO E REXX User s Guide Using Looping Instructions Exercise Using a DO UNTIL Loop Change the exec in the previous exercise Exercise Using a DO WHILE Loop on page 4 15 from a DO WHILE to a DO UNTIL loop and achieve the same results Remember that DO WHILE loops check for true expressions and DO UNTIL loops check for false expressions which means their logical operators are often reversed ANSWER Possible Solution RR kk RRR EERE RR ERR KR ERIK REE RARER REXX KR KKK KARR EEK k RAKE RAKE ER This exec uses a DO UNTIL loop to keep track of window seats in an 8 seat commuter airline x RR kk RRR RRR RRR ERK k k e kk e k k k kk k k k k kk e k k k kk k k k
63. debugging 9 3 used with a command 8 1 used with stack command 11 11 11 16 RESULT 6 7 6 8 8 5 used with EXIT 4 20 SIGL for debugging 9 3 rules syntax 2 3 S SAA Systems Application Architecture general description 1 5 Procedures Language 1 3 SAA Procedures Language 1 5 SAY instruction 2 2 SELECT WHEN OTHERWISE END instruction flowchart 4 6 semicolon to end an instruction 2 5 Service for REXX in MVS 13 1 SETLANG external function valid language codes 10 7 SIGL special variable for debugging 9 3 SIGNAL instruction 4 22 SIGNAL ON ERROR instruction 9 3 SOLDISP 10 12 SOLNUM 10 12 special variable See REXX special variable stack See data stack stem used with OUTTRAP function 10 6 STORAGE external function 10 8 string See literal string SUBCOM command 8 11 subcommand environment See host command environment SUBMIT command 13 7 subroutine calling 4 21 comparison to a function 6 1 6 18 description 6 1 exposing a specific variable 6 6 external 6 3 internal 6 3 passing information using an argument 6 6 passing information to possible problem 6 4 using a variable 6 4 protecting variable 6 5 receiving information from RESULT 6 8 using the ARG built in function 6 7 returning avalue 4 21 using CALL RETURN 6 3 using PROCEDURE 6 5 using PROCEDURE EXPOSE 6 6 when to make internal or external 6 4 writing 6 3 SUBSTR built in function 6 2 SYMDEF 10 5 syntax rules of REXX 2 3 SYSAPPCL
64. enclose the variable in parenthesis in place of a number This variable must be an unsigned integer Therefore use a sign outside the parenthesis to indicate how REXX is to interpret the unsigned integer REXX substitutes the numeric value for the variable as follows quote Ignorance is bliss eoo Pre tne EEA movex 3 variable position PARSE VAR quote part5 10 part6 3 part7 movex part8 part5 contains Ignorance part6 contains is part7 contains bliss part8 contains is bliss Note The variable movex in the previous example must be an unsigned integer Always code a sign prior to the parenthesis to indicate how the integer is to be interpreted If you do not the variable will be interpreted as a string separator Valid signs are A plus sign indicates column movement to the right A minus sign indicates column movement to the left An equal sign indicates an absolute column position For more information about parsing see TSO E REXX Reference SC28 1975 7 8 OS 390 V1R2 0 TSO E REXX User s Guide Parsing Data Parsing Multiple Strings as Arguments When passing arguments to a function or a subroutine you can specify multiple strings to be parsed Arguments are parsed with the ARG PARSE ARG and PARSE UPPER ARG instructions To pass multiple strings separate each string with a comma This comma is not a string separator as illustrated in the example on
65. entire data set To copy an entire existing sequential data set named USERID MY INPUT into a new sequential data set named USERID NEW INPUT and to use the ddnames DATAIN and DATAOUT respectively you could use the following instructions Remember that when the first qualifier of a data set name is your prefix usually your user ID you can omit the first qualifier Copying an Entire Data Set ALLOC DA my input F datain SHR REUSE ALLOC DA new input F dataout LIKE my input NEW NEWSTACK Create a new data stack for input only EXECIO DISKR datain FINIS QUEUE Add a null line to indicate the end of the information EXECIO DISKW dataout FINIS DELSTACK Delete the new data stack FREE F datain dataout If the null line was not queued at the end of the information on the stack the EXECIO command would go to the terminal to get more information and would not end until the user entered a null line 12 8 oS 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information Another way to indicate the end of the information when copying an entire data set is with the QUEUED built in function If the data set is likely to include null lines throughout the data using the QUEUED function is preferable n QUEUED Assign the number of stack items to n EXECIO n DISKW dataout FINIS Also when copying an undetermined number of lines to and from the data
66. example directly followed the first in an exec the value of number would become 12 More about expressions is covered in Using Expressions on page 3 4 Label A label such as Gamel line 5 is a symbolic name followed by a colon A label can contain either single or double byte characters or a combination of single and double byte characters Double byte characters are valid only if you have included OPTIONS ETMODE as the first instruction in your exec A label identifies a portion of the exec and is commonly used in subroutines and functions and with the SIGNAL instruction More about the use of labels appears in Chapter 6 Writing Subroutines and Functions on page 6 1 and SIGNAL Instruction on page 4 22 Null A null is a comment or a blank line which is ignored by the language processor but make an exec easier to read Comments lines 1 through 4 8 through 11 16 A comment begins with and ends with Comments can be on one or more lines or on part of a line You can put information in a comment that might not be obvious to a person reading the REXX instructions Comments at the beginning can describe the overall purpose of the exec and perhaps list special considerations A comment next to an individual instruction can clarify its purpose Note To prevent incompatibilities with CLISTs IBM recommends that all REXX execs start with a comment that includes the characters REXX within the first line line 1
67. expression is broken down by operation as follows gt y gt g value of variable x gt L gt I value of literal 1 gt 0 gt 10 result of operation x 1 gt L gt 5 value of literal 5 gt V gt 2 value of variable y gt 0 gt 10 result of operation 5 y gt 0 gt Q result of final operation 10 10 is false Tracing Results To trace only the final result of an expression use the TRACE R TRACE Results form of the TRACE instruction All expressions that follow the instruction are analyzed and the results are displayed as gt gt gt Final result of an expression If you changed the TRACE instruction operand in the previous example from an I to an R you would see the following results 9 x x IFxt 1 gt 5 y gt gt gt o In addition to tracing operations and results the TRACE instruction offers other types of tracing For information about the other types of tracing with the TRACE instruction see TSO E REXX Reference SC28 1975 Chapter 3 Using Variables and Expressions 3 15 Tracing Expressions with the TRACE Instruction Exercises Using the TRACE Instruction Write an exec with a complex expression such as IF A gt B C lt 2 D THEN Define A B C and D in the exec and use the TRACE instruction ANSWER Possible Solution kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX K RRR RRR RRR kkk k KER kk kkk kkk k kkk kk This exec uses the TRACE instruction to sho
68. have the exec reply with the number of days For month 2 the reply can be 28 or 29 Chapter 4 Controlling the Flow Within an Exec 4 7 Using Looping Instructions ANSWER Possible Solution kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR KERR kkk kkk kkk kkk kkk kk This exec requests the user to enter a month as a whole number from 1 to 12 and responds with the number of days in that x month x RR kk RRR RRR deje k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kk k k kkk kk SAY To find out the number of days in a month SAY Enter the month as a number from 1 to 12 PULL month SELECT WHEN month 9 THEN days 30 WHEN month 4 THEN days 30 WHEN month 6 THEN days 30 WHEN month 11 THEN days 30 WHEN month 2 THEN days 28 or 29 OTHERWISE days 31 END SAY There are days days in Month month Using Looping Instructions There are two types of looping instructions repetitive loops and conditional loops Repetitive loops allow you to repeat instructions a certain number of times and conditional loops use a condition to control repeating All loops regardless of the type begin with the DO keyword and end with the END keyword Repetitive Loops The simplest loop tells the language processor to repeat a group of instructions a specific number of times using a constant following the keyword DO DO 5 SAY Hello END 4 8
69. host command environment and a command only that command is affected After the command is issued the former host command environment becomes active again Issue one command from the ISPF host command environment ADDRESS ispexec edit DATASET dsname Return to the default TSO host command environment ALLOC DA dsname F SYSEXEC SHR REUSE Note Keywords such as DATASET within an ISPF command must be in uppercase when used in a REXX instruction Determining the Active Host Command Environment To find out what host command environment is currently active use the ADDRESS built in function x ADDRESS In this example x is set to the active host command environment for example TSO Checking if a Host Command Environment is Available To check if a host command environment is available before trying to issue commands to that environment issue the TSO E REXX SUBCOM command followed by the name of the host command environment such as ISPEXEC SUBCOM ISPEXEC Chapter 8 Entering Commands from an Exec 8 11 Issuing Other Types of Commands from an Exec If the environment is present the REXX special variable RC returns a O If the environment is not present RC returns a 1 For example when editing a data set before trying to use ISPF PDF edit you can find out if ISPEXEC is available as follows ARG dsname SUBCOM ISPEXEC IF RC 0 THEN ADDRESS ISPEXEC SELECT PGM ISREDIT select ISPF PDF edit
70. instructions EXEC myrexx exec calc 24 55 12 38 exec SAY The result is RC Calc might contain the following instructions ARG numberl number2 number3 number4 answer numberl number2 number3 number4 RETURN answer You might want to invoke an exec with the EXEC command rather than as an external routine when the exec is not within the same PDS as the calling exec or when the PDSs of the two execs are not allocated to either SYSEXEC or SYSPROC Invoking Another Exec Implicitly To implicitly invoke another exec from within an exec type the member name either with or without Because it is treated as a command enclose the member name and the argument if any within quotation marks As with any other implicitly invoked exec the PDSs containing the calling exec and the called exec must be allocated to either SYSEXEC or SYSPROC Remember that a before the member name reduces the search time because fewer files are searched For example to implicitly invoke an exec named MYREXX EXEC CALC and send it an argument of four numbers you could include the following instructions 5calc 24 55 12 38 SAY The result is RC Calc might contain the following instructions ARG numberl number2 number3 number4 answer numberl number2 number3 number4 RETURN answer Chapter 8 Entering Commands from an Exec 8 5 Issuing Other Types of Commands from an Exec Issuing Other Types of Commands from an Exec A REXX
71. interactive trace 9 7 ADDRESS 8 11 ARG 2 17 6 6 6 15 7 4 blank 2 8 CALL RETURN 4 21 comment 2 8 conditional 4 1 continuing to the next line 2 4 DO FOREVER 4 11 DO UNTIL 4 16 DO WHILE 4 14 DO END 4 8 entering 2 3 EXIT 4 20 6 3 6 11 9 8 formatting 2 4 IF THEN ELSE 4 2 INTERPRET 12 2 interrupt 4 1 ITERATE 4 12 LEAVE 4 12 4 18 literal string 2 3 looping 4 1 PARSE 2 15 2 18 PARSE ARG 7 5 PARSE EXTERNAL 11 5 PARSE PULL 7 4 11 3 PARSE UPPER ARG 7 5 PARSE UPPER PULL 7 4 PARSE UPPER VALUE 7 5 X 8 09 390 V1R2 0 TSO E REXX User s Guide REXX instruction continued PARSE UPPER VAR 7 5 PARSE VALUE WITH 7 5 PARSE VAR 7 5 PROCEDURE 6 5 6 13 PROCEDURE EXPOSE 6 6 6 14 PULL 2 16 7 4 11 3 PUSH 11 2 QUEUE 11 2 re executing during interactive trace 9 7 SAY 2 2 SELECT WHEN OTHERWISE END 4 6 SIGNAL 4 22 SIGNAL ON ERROR 9 3 syntax 2 3 TRACE ending tracing 9 8 interactive tracing 9 4 tracing command 9 2 tracing expression 3 14 type of assignment 2 7 command 2 8 keyword 2 7 label 2 8 null 2 8 using blank 2 4 using comma 2 4 using quotation mark 2 3 8 2 using semicolon 2 5 writing 2 3 REXX language comparison to CLIST C 1 description 1 1 example use of uppercase and lowercase xiv exec description xiii 2 2 feature of 1 1 program exec xiii REstructured eXtended eXecutor xiii SAA Systems Application Architecture xiii 1 3 REXX program portability of 1 4 REXX special variable RC for
72. internal function it is important to end the main part of the exec with the EXIT instruction Chapter 6 Writing Subroutines and Functions 6 11 Writing a Function The following illustrates an external function named func2 REXX EXEC MAIN instruction s x func2 arg1 instruction s exit Y REXX EXEC FUNC2 ARG varl instruction s RETURN value To determine whether to make a function internal or external you might consider factors such as e Size of the function Very large functions often are external whereas small functions fit easily within the calling exec How you want to pass information It is quicker to pass information through variables in an internal function This method is described in the next topic under Passing Information by Using Variables Whether the function might be of value to more than one exec or user If so an external function is preferable Performance The language processor searches for an internal function before it searches for an external function For the complete search order of functions see Search Order for Functions on page 10 17 Passing Information to a Function When an exec and its internal function share the same variables you can use commonly shared variables to pass information between caller and internal function The function does not need to pass arguments within the parentheses that follow the funct
73. message depending on the message type you specify The message text and associated information are stored in variables which can be displayed or used within the REXX exec The function call is replaced by a function code that indicates whether the call was successful See TSO E REXX Reference SC28 1975 for more information about the syntax function codes and variables for GETMSG You must have CONSOLE command authority to use the GETMSG function Before you issue GETMSG you must Use the TSO E CONSPROF command to specify the types of messages that are not to be displayed at the terminal The CONSPROF command can be used before you activate a console session and during a console session if values need to be changed e Use the TSO E CONSOLE command to activate an extended MCS console session The GETMSG function can be used only in REXX execs that run in the TSO E address space Using the LISTDSI Function You can use the LISTDSI list data set information function to retrieve detailed information about a data set s attributes The attribute information is stored in variables which can be displayed or used within instructions The function call is replaced by a function code that indicates whether the call was successful The LISTDSI function can be used only in REXX execs that run in the TSO E address space To retrieve the attribute information include the data set name within parentheses after LISTDSI When you specify a fu
74. number number Add the number to 0 Using numeric constants and arithmetic operators you can write arithmetic expressions as follows 7 2 result is 9 x 7 2 result is 5 x 7 2 result is 14 7 2 result is 49 x 7 2 5 result is an error Division Notice that three operators represent division Each operator displays the result of a division expression in a different way I Divide and express the answer possibly as a decimal number For example 7 2 result is 3 5 6 2 result is 3 Divide and express the answer as a whole number The remainder is ignored For example 752 result is 3 x Divide and express the answer as the remainder only For example 7 2 result is 1 x Order of Evaluation When you have more than one operator in an arithmetic expression the order of numbers and operators can be critical For example in the following expression which operation does the language processor perform first 7 2 9 3 1 Proceeding from left to right it is evaluated as follows Expressions within parentheses are evaluated first Expressions with operators of higher priority are evaluated before expressions with operators of lower priority Chapter 3 Using Variables and Expressions 3 5 Using Expressions Arithmetic operator priority is as follows with the highest first Arithmetic Operator Priority Prefix operators iis Power exponential 96
75. of the exec The variables number1 number2 and answer are shared r Example of Passing Information in a Variable kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR RRR RRR KER RRR kkk kkk ERE kk This exec receives a calculated value from an internal subroutine and displays that value x RR kk RRR RRR REE RRR k ke kk de k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk numberl 5 number2 10 CALL subroutine SAY answer Displays 15 EXIT subroutine answer numberl number2 RETURN Using the same variables in an exec and its internal subroutine can sometimes create problems In the following example the main part of the exec and the subroutine use the same control variable i for their DO loops As a result the DO loop repeats only once in the main exec because the subroutine returns to the main exec with i 6 6 4 08 390 V1R2 0 TSO E REXX User s Guide Writing a Subroutine r Example of a Problem Caused by Passing Information in a Variable kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX K RRR KIRK RRR KK KER RRR kkk kkk kkk kk NOTE This exec contains an error x It uses a DO loop to call an internal subroutine and the x subroutine also uses a DO loop with same control variable as x the main exec The DO loop in the main exec repeats only once jokes e k k e kk de k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk
76. of the exec Failure to do so can lead to unexpected or unintended results in your REXX exec This type of comment is called the REXX exec identifier and immediately identifies the program to readers as a REXX exec and also distinguishes it from a CLIST It is necessary to distinguish execs from CLISTs when they are both stored in the system file SYSPROC For more information about where and how execs are stored see Running an Exec Implicitly on page 2 12 e Blank lines lines 6 18 Blank lines help separate groups of instructions and aid readability The more readable an exec the easier it is to understand and maintain Command An instruction that is not a keyword instruction assignment label or null is processed as a command and is sent to a previously defined environment for processing For example the word TIME in the previous exec line 16 even though surrounded by comments is processed as a TSO E command TSO system TIME command 2 8 OS 390 V1R2 0 TSO E REXX User s Guide Execs Using Double Byte Character Set Names More information about issuing commands appears in Chapter 8 Entering Commands from an Exec on page 8 1 Execs Using Double Byte Character Set Names You can use double byte character set DBCS names in your REXX execs for literal strings labels variable names and comments Such character strings can be single byte double byte or a combination of both single and double byte
77. of the various uses of EXECIO and the type of data set allocation appropriate for these uses are shown in and after Copying Information From One Data Set to Another on page 12 8 If you use EXECIO to read information from a data set and to the data stack the information can be stored in FIFO or LIFO order on the data stack FIFO is the default If you use EXECIO to read information from a data set and to a list of variables the first data set line is stored in variable1 the second data set line is stored in variable2 and so on Data read into a list of variables can be accessed randomly After the information is in the data stack or in a list of variables the exec can test it copy it to another data set or update it before returning it to the original data set Reading Information from a Data Set To read information from a data set to the data stack or to a list of variables use EXECIO with either the DISKR or DISKRU operand A typical EXECIO command to read all lines from the data set allocated to the ddname MYINDD might appear as EXECIO DISKR myindd FINIS The rest of this topic describes the types of information you can specify with EXECIO DISKR and EXECIO DISKRU For further information see TSO E REXX Reference SC28 1975 How to specify the number of lines to read To open a data set without reading any records put a zero immediately following the EXECIO command and specify the OPEN operand EXECIO DISKR mydd OPE
78. or in one of various optional formats TRACE Returns the trace actions currently in effect USERID Returns the TSO E user ID if the REXX exec is running in the TSO E address space VALUE Returns the value of a specified symbol and optionally assigns it a new value XRANGE Returns a string of all 1 byte codes in ascending order between and including specified starting and ending values Indicates a non SAA built in function provided only by TSO E Chapter 5 Using Functions 5 7 Built In Functions Testing Input with Built In Functions Some of the built in functions provide a convenient way to test input When an interactive exec requests input the user might respond with input that is not valid For instance in the example Using Comparison Expressions on page 3 8 the exec requests a dollar amount with the following instructions SAY What did you spend for lunch yesterday SAY Please do not include the dollar sign PARSE PULL last If the user responds with a number only the exec will process that information correctly If the user responds with a number preceded by a dollar sign or with a word such as nothing the exec will return an error To avoid getting an error you can check the input with the DATATYPE function as follows DO WHILE DATATYPE last NUM SAY Please enter the lunch amount again SAY The amount you entered was not a number without a dollar sign PARSE PULL last END O
79. processor evaluates each operation For information about using the TRACE instruction to evaluate expressions see Tracing Expressions with the TRACE Instruction on page 3 14 For information about using the TRACE instruction to evaluate host commands see the next section Tracing Commands with the TRACE Instruction on page 9 2 Special variables RC and SIGL are set by the system to indicate The return code from a command RC The line number from which there was a transfer of control because of a function call a SIGNAL instruction or a CALL instruction SIGL The TSO E command EXECUTIL TS Trace Start and EXECUTIL TE Trace End control the interactive debug facility as do various options of the TRACE instruction For more information about interactive debug see Tracing with the Interactive Debug Facility on page 9 4 Copyright IBM Corp 1988 1996 9 1 Debugging Execs Tracing Commands with the TRACE Instruction The TRACE instruction has many options for various types of tracing two of which are commands or c and error or e TRACE C When you specify trace c in an exec any command that follows is traced before it is executed then it is executed and the return code from the command is displayed When an exec without trace c issues an incorrect TSO E command the exec ends with a TSO E error message For example a LISTDS command specifies an incorrect data set name LISTDS
80. quotation marks and other commands such as ALLOCATE require single quotation marks around fully qualified data set names EXEC myrexx exec add 25 78 33 exec ALLOC DA USERID MYREXX EXEC F SYSEXEC SHR REUSE As REXX instructions these commands can be entirely enclosed in double quotation marks and still retain the single quotation marks for the specific information within the command For this reason it is recommended that as a matter of course you enclose TSO E commands with double quotation marks EXEC myrexx exec add 25 78 33 exec ALLOC DA USERID MYREXX EXEC F SYSEXEC SHR REUSE Remember that data set names beginning with your prefix usually your user ID can be specified without the prefix and without quotation marks ALLOC DA MYREXX EXEC F SYSEXEC SHR REUSE More about data sets names and when to enclose them in quotation marks is covered in the next topic Passing Data Set Names as Arguments How you pass a data set name as an argument depends on the way you specify the data set name and whether you invoke the exec explicitly or implicitly Ways to specify the data set name are controlled by the TSO E naming conventions which define fully qualified and non fully qualified data sets A 8 2 OS 390 V1R2 0 TSO E REXX User s Guide Issuing TSO E Commands from an Exec fully qualified data set name specifies all three qualifiers including the prefix and must appear within a set of quotation marks use
81. run outside of a TSO E address space keep in mind the following exceptions to information in this part of the book An exec that runs outside of a TSO E address space cannot include TSO E commands ISPF commands or ISPF PDF edit commands An exec that runs outside of a TSO E address space can include TSO E commands if you use the TSO E environment service see note An exec that runs outside of TSO E cannot include most of the TSO E external functions For information about the functions you can use in TSO E and non TSO E address spaces see Services Available to REXX Execs on page 13 1 In TSO E several REXX instructions either display information on the terminal or retrieve information that the user enters at the terminal In a non TSO E address space these instructions get information from the input stream and write information to the output stream SAY this instruction sends information to the output DD whose default is SYSTSPRT PULL this instruction gets information from the input DD whose default is SYSTSIN TRACE this instruction sends information to the output DD whose default is SYSTSPRT PARSE EXTERNAL this instruction gets information from the input DD whose default is SYSTSIN e An exec that runs outside of TSO E cannot interact with CLISTs Copyright IBM Corp 1988 1996 Note You can use the TSO E environment service IKJTSOEV to create a TSO E environment in a non TSO
82. space appears below the data set name the data set is allocated to the previously specified file DDNAME 2 Write down the names of the data sets at your installation that are allocated to SYSEXEC First data set Remaining data sets 3 Write down the names of the data sets at your installation that are allocated to SYSPROC First data set Remaining data sets Appendix A Allocating DataSets A 3 4 Issue the LISTDS command for the first data set in each system file to display the record format logical record length and block size To see the attributes of data sets used at your installation issue the LISTDS command for the first data set in each system file concatenation to display something like the following READY LISTDS sysexec first exec SYSEXEC FIRST EXEC RECFM LRECL BLKSIZE DSORG VB 255 5100 PO VOLUMES TS0026 READY LISTDS sysproc first clist SYSPROC FIRST CLIST RECFM LRECL BLKSIZE DSORG FB 80 19040 PO VOLUMES TSOLO7 5 Write down the attributes of the first data set in your SYSEXEC concatenation RECFM LRECL BLKSIZE 6 Write down the attributes of the first data set in your SYSPROC concatenation RECFM LRECL BLKSIZE r Please Note Save this information for use with the following checklists A 4 09 390 V1R2 0 TSO E REXX User s Guide Checklist 1 Creating and Editing a Data Set Using ISPF PDF 1 Select the ISPF PDF DATASET UTILITIES opti
83. stack it is a good idea to use the NEWSTACK and DELSTACK commands to prevent removing items previously placed on the stack For more information about these commands see Protecting Elements in the Data Stack on page 11 14 Copying a specified number of lines to a new data set To copy 10 lines of data from an existing sequential data set named DEPT5 STANDARD HEADING to a new member in an existing PDS named USERID OFFICE MEMO JAN15 and use the ddnames INDD and OUTDD respectively you could use the following instructions Remember that a data set name that does not begin with your prefix must be enclosed in single quotes Copying 10 Lines of Data to a New Data Set ALLOC DA dept5 standard heading F indd SHR REUSE ALLOC DA office memo jani5 F outdd SHR REUSE EXECIO 10 DISKR indd FINIS EXECIO 10 DISKW outdd FINIS To copy the same 10 lines of data to a list of compound variables with the stem data substitute the following EXECIO commands EXECIO 10 DISKR indd FINIS STEM DATA EXECIO 10 DISKW outdd FINIS STEM DATA Note When copying information to more than one member of a PDS only one member of the PDS should be open at a time Adding 5 lines to the end of an existing sequential data set To add 5 lines from an existing data set member named USERID WEEKLY INPUT MAR28 to the end of an existing sequential data set named USERID YEARLY OUTPUT and use the ddnames MYINDD and MYOUTDD respectively
84. this instruction sends information to the output DD whose default is SYSTSPRT PULL this instruction gets information from the input DD whose default is SYSTSIN TRACE this instruction sends information to the output DD whose default is SYSTSPRT PARSE EXTERNAL this instruction gets information from the input DD whose default is SYSTSIN The USERID built in function instead of returning a user identifier might return a stepname or jobname Note You can use the TSO E environment service IKJTSOEV to create a TSO E environment in a non TSO E address space If you run a REXX exec in the TSO E environment you created the exec can contain TSO E commands external functions and services that an exec running in a TSO E address space can use That is the TSO host command environment ADDRESS TSO is available to the exec For more information about the TSO E environment service and the different considerations for running REXX execs within the environment see TSO E Programming Services SC28 1971 Copyright IBM Corp 1988 1996 OS 390 V1R2 0 TSO E REXX User s Guide Features of REXX Chapter 1 Introduction What is REXX 2 bh Aone er RES Re ad oe Oe Puedes Eee 1 1 Features of REXX tu xu be eo eee Lee mee Ae ey 1 1 Ease ofuse e 42 noL bod et de AGA OE eo er AGES ens 1 1 Free format waa ee be eae eae eRe Sine EG Ross 1 2 Convenient built in functions 2 202 200 220005 1 2 Debugging
85. this one and ii the mutual use of the information which has been exchanged should contact IBM Informationssysteme GmbH Abteilung Recht 0215 Pascalstr 100 70569 Stuttgart Federal Republic of Germany Such information may be available subject to appropriate terms and conditions including in some cases payment of a fee For online versions of this book we authorize you to Copy modify and print the documentation contained on the media for use within your enterprise provided you reproduce the copyright notice all warning statements and other required statements on each copy or partial copy Transfer the original unaltered copy of the documentation when you transfer the related IBM product which may be either machines you own or programs if the program s license terms permit a transfer You must at the same time destroy all other copies of the documentation You are responsible for payment of any taxes including personal property taxes resulting from this authorization THERE ARE NO WARRANTIES EXPRESS OR IMPLIED INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE O Copyright IBM Corp 1988 1996 xi Some jurisdictions do not allow the exclusion of implied warranties so the above exclusion may not apply to you Your failure to comply with the terms above terminates this authorization Upon termination you must destroy your machine readable documentation Programming Int
86. with Built In Functions llle 5 8 Chapter 6 Writing Subroutines and Functions 6 1 What are Subroutines and Functions 20 6 1 When to Write Subroutines vs Functions 6 2 Writing a Subroutine s 6 3 Passing Information to a Subroutine sr 6 4 Receiving Information from a Subroutine sn 6 8 Writing a Function mi oe Re 6 11 Passing Information to a Function 0 6 12 Receiving Information from a Function llle 6 16 Summary of Subroutines and Functions 6 18 Chapter 7 Manipulating Data ollis 7 1 Using Compound Variables and Stems 7 1 What is a Compound Variable ollis 7 1 iV OS 390 V1R2 0 TSO E REXX User s Guide Using Stems 2 24445 svi domuum Ws be SOS eS Bd aT 7 2 Parsing Data oce aet ane mE Po UR Oe BA de ds 7 4 Instructions that Parse les 7 4 Ways of Parsing 2 4 ns oes EE Re Yos e eee kB II e Re qx 7 6 Parsing Multiple Strings as Arguments llli 7 9 Part 2 PART Il Using REXX Chapter 8 Entering Commands from an Exec 8 1 Types of Commands es 8 1 Issuing TSO E Commands from an Exec 222004 8 2 Using Quotations Marks in Commands sls 8 2 Using Variables in Commands sls 8 3 Causing Interactive Comma
87. 0 6 3 6 11 explicit execution EXEC command 2 11 from ISPF PDF command line 2 11 from ISPF PDF command option 2 11 from READY 2 11 expression arithmetic 3 4 order of evaluation 3 5 Boolean 3 10 comparison 3 7 concatenation 3 12 definition 3 4 logical 3 10 tracing 3 14 external function TSO E description 10 1 GETMSG 10 2 LISTDSI 10 2 MSG 10 4 OUTTRAP 10 6 PROMPT 10 7 SETLANG 10 7 STORAGE 10 8 SYSDSN 10 9 SYSVAR_ 10 10 external subroutine 6 3 F FIFO first in first out 11 1 X 4 08 390 V1R2 0 TSO E REXX User s Guide file See system file file I O See EXECIO foreground processing explicit execution 13 3 implicit execution 13 3 of anexec 13 3 function ADDRESS built in 8 11 ARG built in 6 7 6 16 argument 5 1 built in arithmetic 5 4 comparison 5 5 conversion 5 5 formatting 5 5 string manipulating 5 6 testing input with 5 8 comparison to a subroutine 6 1 6 18 description 6 1 built in 5 1 function package 5 1 10 17 TSO E external 5 1 10 1 user written 5 1 exposing a specific variable 6 14 external 6 12 internal 6 11 passing information to 6 15 possible problem 6 13 using a variable 6 12 PROMPT 8 4 protecting a variable 6 13 QUEUED built in 11 3 11 10 receiving information from using the ARG built in function 6 16 returning a value 5 2 search order 10 17 TSO E external description 10 1 GETMSG 10 2 LISTDSI 10 2 MSG 10 4 MVSVAR 10 5 OUTTRAP 10 6 PROMPT 10 7 SETLANG 10 7 STORAGE 10 8 SYSCPUS 10 8
88. 05 390 TSO E REXX User s Guide il Note Before using this information and the product it supports be sure to read the general information under Notices on page xi First Edition September 1996 This edition applies to Release 2 of OS 390 5645 001 and to all subsequent releases and modifications until otherwise indicated in new editions Order publications through your IBM representative or the IBM branch office serving your locality Publications are not stocked at the address below IBM welcomes your comments A form for readers comments may be provided at the back of this publication or you may address your comments to the following address IBM Deutschland Entwicklung GmbH Department 3248 Sch naicher Str 220 D 71032 B blingen Federal Republic of Germany Or by FAX From Germany 07031 16 3456 Other countries 49 7031 16 3456 Or electronically IBM Mail Exchange DEIBMBMO at IBMMAIL Internet e mail vsepubs vnet ibm com If you would like a reply be sure to include your name address telephone number or FAX number Make sure to include the following in your comment or note Title and order number of this book Page number or topic related to your comment When you send information to IBM you grant IBM a nonexclusive right to use or distribute the information in any way it believes appropriate without incurring any obligation to you Copyright International Business Machines
89. 4 05 390 V1R2 0 TSO E REXX User s Guide Specifying Alternative Exec Libraries Appendix B Specifying Alternate Libraries with the ALTLIB Command Specifying Alternative Exec Libraries with the ALTLIB Command B 1 Using the ALTLIB Command llle B 1 Stacking ALTLIB Requests lll llle B 2 Using ALTLIB with ISPF l llle B 2 Examples of the ALTLIB Command The ALTLIB command gives you more flexibility in specifying exec libraries for implicit execution With ALTLIB a user or ISPF application can easily activate and deactivate exec libraries for implicit execution as the need arises This flexibility can result in less search time when fewer execs are activated for implicit execution at the same time In addition to execs the ALTLIB command lets you specify libraries of CLISTs for implicit execution Specifying Alternative Exec Libraries with the ALTLIB Command The ALTLIB command lets you specify alternative libraries to contain implicitly executable execs You can specify alternative libraries on the user application and system levels e The user level includes exec libraries previously allocated to the file SYSUEXEC or SYSUPROC During implicit execution these libraries are searched first The application level includes exec libraries specified on the ALTLIB command by data set or file name During implicit execution these libraries are searched after user libraries The syst
90. ACE instruction or with the TSO E EXECUTIL TS command When interactive tracing is initiated with the TRACE instruction interactive tracing is not carried over into external routines that are called but is resumed when the routines return to the traced exec When interactive trace is initiated by the EXECUTIL TS command interactive trace continues in all external routines called unless a routine specifically ends tracing Option of the TRACE Instruction One way to start interactive tracing is to include in an exec the TRACE instruction followed by a question mark and a trace option For example TRACE I TRACE Intermediates The question mark must precede the option with no blanks in between Interactive tracing then begins for the exec but not for external routines the exec calls The following example includes a TRACE R TRACE Results instruction to interactively trace the result of each instruction 9 4 08 390 V1R2 0 TSO E REXX User s Guide Debugging Execs r Example of Interactive Trace kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXXAR RRR RRR kkk kk kkk kkk kkk kkk This exec receives as arguments the destination and the name x of a data set It then interactively traces the transmitting X that data set to the destination and the returning of a message that indicates whether the transmit was successful x RR RR RRR RRR ERR ERR RR ERIK REI kk RIAA KER IK KKK IK KK RIKKI k kk kkk KERR TRACE R ARG dest d
91. B and logical record length LRECL Also the first data set in the list can determine the block size BLKSIZE for the data sets that follow If the block size of the first data set is smaller than the block sizes of subsequent data sets you might end in error To avoid error use the Preliminary Checklist and the other checklists provided and follow directions carefully A 12 09 390 V1R2 0 TSO E REXX User s Guide 2 Execute SETUP by entering the following EXEC command READY hp2 EXEC rexx exec setup exec If the allocation was successful you should then see displayed on your screen Allocation to SYSPROC completed To have SETUP execute when you log on and automatically allocate your data set to SYSPROC type the same EXEC command in the COMMAND field of your LOGON panel TSO E LOGON PF1 PF13 gt Help PF3 PF15 gt Logoff PA1 gt Attention PA2 gt Reshow You may request specific HELP information by entering a in any entry field ENTER LOGON PARAMETERS BELOW RACF LOGON PARAMETERS USERID gt YOURID PASSWORD gt NEW PASSWORD gt PROCEDURE gt MYPROC GROUP IDENT gt ACCT NMBR gt 00123 SIZE gt 5800 PERFORI gt COMMAND gt EXEC rexx exec setup exec ENTER AN S BEFORE EACH OPTION DESIRED BELOW NOMAIL NONOTICE RECONNECT OIDCARD Appendix A Allocating DataSets A 13 A 1
92. CLIST 2 8 identifying as an exec 2 8 to clarify the purpose of an exec 2 8 comparison operator equal 3 8 false 0 3 7 strictly equal 3 8 true 1 3 7 types of 3 7 compiler benefits 1 3 compound variable changing all variables in an array 7 2 description 7 1 initializing 7 1 used in EXECIO command 12 5 12 7 12 10 used in LISTDSI 10 6 using stems 7 2 concatenation of datasets A 1 concatenation operator type of 3 12 abuttal 3 12 blank 3 12 CONSOLE host command environment 8 7 console session 8 7 continuation of an instruction 2 4 control variable See TSO E external function copy information to and from data sets 12 8 information to compound variables 12 10 information to the end of a data set 12 9 CPICOMM host command environment 8 7 8 9 D data set adding information with EXECIO command 12 9 adding to SYSEXEC A 10 adding to SYSPROC A 12 allocating 2 1 A 1 attributes A 6 concatenation A 10 A 12 copying information with EXECIO command 12 8 creating 2 1 A 1 creating in ISPF PDF A 5 creating with ALLOCATE A 9 creating with the ALLOCATE command A 9 editing A 7 finding the allocation status of A 3 fully qualified vs non fully qualified 8 2 library A 1 data set continued name as argument 8 2 naming convention 8 2 partitioned PDS A 1 prefix 8 2 reading information from with EXECIO 12 3 sequential A 1 to contain an exec 2 1 updating information with EXECIO command 12 10 writing information to with EXECIO
93. Corporation 1988 1996 All rights reserved Note to U S Government Users Documentation related to restricted rights Use duplication or disclosure is subject to restrictions set forth in GSA ADP Schedule Contract with IBM Corp Contents Notices isade ot Bee oe ee ES feeesed4e4qu see Sg qiierrsS xi Programming Interface Information 0 000004 xii Trademarks sul Pe Skok eto SERGE BLA Swe nee XA Ren xii About This Book i a D ls xiii Who Should Use This Book ooo len xiii How This Book Is Organized llle xiii Where to Find More Information lll xiv Referenced Program Products aaa xiv Elements in O9 890 zoo Reb tng Gh te a Re ipud XV Summary of Changes 2 0200000 2a xvii Changes to SC28 1974 00 for OS 390 Release2 xvii Part 1 PART I Learning the REXX Language Chapter 1 Introduction oll lll leen 1 1 Whatis REXXQ ease uie ha due Box woe Te el au ae 2G we d 1 1 Feal resof REXX ni sdodoetedoex eta ebb Sa eae uo d 1 1 Faso ol USE dos muet deir due du eae dele wk ew a dex ue ed 1 1 Ereeformat 55 oe modb S hoe a eR eR E S d eu 1 2 Convenient built in functions ole 1 2 Debugging capabilities 2 2 2 2 2 2 2 2 222 0 000000 008 1 2 Interpreted language aaa 1 2 Extensive parsing capabilities sss 1 2 Components of REXX 000000 ss 1 2 The SAA So
94. DS THEN heads 0 tails 1 choose a random number between 0 and 1 user chose correctly user didn t choose correctly 6 10 05 390 v1R2 0 TSO E REXX User s Guide Writing a Function Writing a Function A function is a series of instructions that an exec invokes to perform a specific task and return a value As was described in Chapter 5 Using Functions on page 5 1 a function may be built in or user written An exec invokes a user written function the same way it invokes a built in function by the function name immediately followed by parentheses with no blanks in between The parentheses can contain up to 20 arguments or no arguments at all function argumentl argument2 or function A function requires a returned value because the function call generally appears in an expression x function argumentsl argument2 When the function ends it may use the RETURN instruction to send back a value to replace the function call instruction s x funcl argl arg2 instruction s EXIT Y Funcl instruction s RETURN value Lo LJ Functions may be internal and designated by a label or external and designated by the data set member name that contains the function The previous example illustrates an internal function named func1 IMPORTANT NOTE Because internal functions generally appear after the main part of the exec when you have an
95. DS is specified in the allocation they are concatenated or logically connected in the order in which they are specified The association of the PDS to the system file remains for the duration of your terminal session or until another ALLOCATE command alters the association You can allocate a data set to a system file in the foreground with the TSO E ALLOCATE command or in the background with a JCL DD statement You cannot use ISPF PDF to allocate a data set to a system file Copyright IBM Corp 1988 1996 A 1 Where to Begin Checklists for allocating a data set to SYSEXEC and SYSPROC appear in Checklist 3 Writing an Exec that Sets up Allocation to SYSEXEC on page A 10 Checklist 4 Writing an Exec that Sets up Allocation to SYSPROC on page A 12 Where to Begin Before creating a PDS in which to store your execs use the Preliminary Checklist on page A 3 to find out information that you can use to make your PDS compatible with other PDSs at your installation Then create a PDS with either Checklist 1 Creating and Editing a Data Set Using ISPF PDF on page A 5 or Checklist 42 Creating a Data Set with the ALLOCATE Command on page A 9 After the PDS is created if you want to be able to invoke those execs implicitly during that terminal session you must allocate the PDS to a system file SYSEXEC or SYSPROC The allocation is temporary and must be established for each terminal session One way to estab
96. E address space If you run a REXX exec in the TSO E environment you created the exec can contain TSO E commands external functions and services that an exec running in a TSO E address space can use That is the TSO host command environment ADDRESS TSO is available to the exec with some limitations For more information about the TSO E environment service limitations on the environment it creates and the different considerations for running REXX execs within the environment see TSO E Programming Services SC28 1971 OS 390 V1R2 0 TSO E REXX User s Guide Types of Commands Chapter 8 Entering Commands from an Exec Types of Commands es 8 1 Issuing TSO E Commands from an Exec 2 222004 8 2 Using Quotations Marks in Commands ssl 8 2 Passing Data Set Names as Arguments 8 2 Using Variables in Commands len 8 3 Causing Interactive Commands to Prompt the User 8 4 Invoking Another Exec as a Command 8 5 Invoking Another Exec with the EXEC Command 8 5 Invoking Another Exec Implicitly 2 0 8 5 Issuing Other Types of Commands from an Exec 8 6 What is a Host Command Environment 8 6 APPC MVS Host Command Environments 8 8 Examples Using APPC MVS Services 8 10 Changing the Host Command Environment
97. EN T MUR URN NEA UG REXX RENAE ERLE RE CAE UNS KON E This exec receives as arguments the length and width of a Eni rectangle and passes that information to an internal function named perimeter The function then calculates the perimeter of me the rectangle J RESERERER ER EE NERE ERASER ASR RALEA EEA AGIR E EE EROGO ICE ARR AA DER OUR GO ARERR PARSE ARG long wide NE NM SAY The perimeter is perimeter long wide inches EXIT perimeter ARG length width perim 2 length 2 width RETURN did Notice the positional relationships between long and length and wide and width Also notice that information is received from variable perim to replace the function call Chapter 6 Writing Subroutines and Functions 6 15 Writing a Function Using the ARG Built in Function Another way for a function to receive arguments is with the ARG built in function This built in function returns the value of a particular argument specified by a number that represents the argument position For instance in the previous example instead of the ARG instruction ARG length width you can use the ARG function as follows length ARG 1 puts the first argument into length width ARG 2 puts the second argument into width More information about the ARG function appears in TSO E REXX Reference SC28 1975 Receiving Information from a Function Although a function can receive up to 20 argumen
98. END Copyright IBM Corp 1988 1996 4 1 Using Conditional Instructions Looping instructions which tell the language processor to repeat a set of instructions A loop can repeat a specified number of times or it can use a condition to control repeating REXX looping instructions are DO expression END DO FOREVER END DO WHILE expression true END DO UNTIL expression true END Interrupt instructions which tell the language processor to leave the exec entirely or leave one part of the exec and go to another part either permanently or temporarily The REXX interrupt instructions are EXIT SIGNAL abel CALL abel RETURN Using Conditional Instructions There are two types of conditional instructions IF THEN ELSE can direct the execution of an exec to one of two choices SELECT WHEN OTHERWISE END can direct the execution to one of many choices IF THEN ELSE Instructions The examples of IF THEN ELSE instructions in previous chapters demonstrated the two choice selection In a flow chart this appears as follows False True lt expression ELSE THEN instruction instruction As a REXX instruction the flowchart example looks like IF expression THEN instruction ELSE instruction You can also arrange the clauses in one of the following ways to enhance readability IF expression THEN instruction ELSE instruction or IF expression THEN instruction ELSE instruction 4 2 OS
99. Example 5 continued 12 17 EXECIO Example 6 lens 12 18 EXECIO Example 6 continued 12 19 EXECIO Example 6 continued 12 20 ix X OS 390 V1R2 0 TSO E REXX User s Guide Notices References in this publication to IBM products programs or services do not imply that IBM intends to make these available in all countries in which IBM operates Any reference to an IBM product program or service is not intended to state or imply that only IBM s product program or service may be used Any functionally equivalent product program or service that does not infringe any of IBM s intellectual property rights may be used instead of the IBM product program or service Evaluation and verification of operation in conjunction with other products programs or services except those expressly designated by IBM are the user s responsibility IBM may have patents or pending patent applications covering subject matter in this document The furnishing of this document does not give you any license to these patents You can send license inquiries in writing to the IBM Corporation Mail Station P131 522 South Road Poughkeepsie NY 12601 5400 USA Attention Information Request Licensees of this program who wish to have information about it for the purpose of enabling i the exchange of information between independently created programs and other programs including
100. External Functions 10 15 Additional Examples r Example 3 Using the OUTTRAP Function kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX K RRR RRR RRR kkk k KER RRR kkk kkk kkk kk This exec lists datasets allocated to a ddname that is passed as an argument when the exec is invoked It uses the OUTTRAP function to trap output from the LISTA STATUS command It then loops through the output looking for a match to the input ddnamex When match is found the exec will SAY the name of all datasets allocated to that ddname The LISTA STATUS command produces output of the form DATASET NAME ALLOCATED TO DDNAME x DDNAME DISP x In this output when the area for DDNAME is blank then the data set is allocated to the previous DDNAME that was not blank This condition is one of the tests in the program below EK kk k k e e ek e e k e kk k k k e kk e k k k kk k k k k KERIKERI k k kk k k k k kk k k k k kk kkk k kkk kk ARG ddname x OUTTRAP ddlist start output trapping into DDLIST LISTA STATUS issue the LISTA command x x OUTTRAP OFF turn off output trapping x done NO initialize loop control variable DO i 1 TO ddlist O WHILE done NO IF words ddlist i 2 amp ddname word ddlist i 1 THEN DO if there is a DDNAME amp it matches firstdataset i 1 back up to first dataset name x SAY ddlist firstd
101. For example 4 2 amp a a true so result is 1 2 4 amp a a false so result is 0 Inclusive OR Returns 1 if at least one comparison is true For example 4 gt 2 5 23 at least one is true so result is 1 2 4 5 23 neither one is true so result is 0 Exclusive OR Returns 1 if only one comparison but not both is true For example 4 gt 2 amp amp 5 3 only one is true so result is 1 4 2 8 amp 5 5 both are true so result is 0 2 gt 4 8 amp 5 3 neither one is true so result is 0 Logical NOT Returns the opposite response For example 0 opposite of 0 so result is 1 4 gt 2 opposite of true so result is 0 Using Logical Expressions Logical expressions are used in complex conditional instructions and can act as checkpoints to screen unwanted conditions When you have a series of logical expressions for clarification use one or more sets of parentheses to enclose each expression IF A lt B 2 D amp M Q M D THEN 3 10 os 390 V1R2 0 TSO E REXX User s Guide Using Expressions The following example uses logical operators to make a decision r Example Using Logical Expressions kk kkk kkk kkk kkk kkk kk kkk kkk k kkk REXX RRR RRR RRR RRR KER k k k RARER ER ERR This exec receives arguments for a complex logical expression that determines whether a person should go ski
102. GC28 1726 Product Name and Level Name in OS 390 Base or Optional BookManager BUILD MVS V1R3 BookManager BUILD optional BookManager READ MVS V1R3 BookManager READ base MVS Bulk Data Transfer V2 Bulk Data Transfer BDT base MVS Bulk Data Transfer File to File V2 Bulk Data Transfer BDT File to File optional MVS Bulk Data Transfer SNA NJE V2 Bulk Data Transfer BDT SNA NJE optional IBM C C for MVS ESA V3R2 C C optional DFSMSdfp V1R3 DFSMSdfp base DFSMSdss DFSMSdss optional DFSMShsm DFSMShsm optional DFSMSrmm DFSMSrmm optional DFSMS MVS Network File System V1R3 DFSMS MVS Network File System base DFSORT DFSORT optional EREP MVS V3R5 EREP base FFST MVS V1R2 FFST MVS base GDDM MVS V3R1 2 GDDM base GDDM OS 2 LINK e GDDM PCLK GDDM PGF GDDM optional GDDM REXX MVS V3R1 2 GDDM REXX optional IBM High Level Assembler for MVS V1R2 High Level Assembler base IBM High Level Assembler Toolkit High Level Assembler Toolkit optional ICKDSF R16 ICKDSF base ISPF V4R2 ISPF base Language Environment for MVS V1R6 Language Environment base Language Environment V1R5 Data Decryption Language Environment Data Decryption optional MVS ESA SP V5R2 2 e BCP BCP or MVS base e ESCON Director Support e ESCON Director Support base Hardware Configuration Definition HCD Hardware Configuration Definition HCD base JES2 V5R2 0 e JES2 base e JES3 V5R2 1 e JES3 optional
103. HR REUSE input file 2 ALLOC FI myoutdd DA all sample data MOD REUSE output append file x RR k RRR RR ke deed KERIKERI KERIKERI KKK AK KIKI IKK EA k kk k EKER Read all records from samplel data and append them to the x end of all sample data x RR RA RRR RRR RRR deje e kk e ke k k kk k k k ke k k e k k k kk k k k k kk k k k k kk k k k k kk k kk k kkk kk exec RC 0 Initialize exec return code EXECIO DISKR myinddl STEM newvar FINIS Read all records IF rc 0 THEN If read was successful DO RRR k k ek e RRR EAR R EERE R ERIK KR RAK k k k k kk k ERIK k kk k k k k KIRKE kkk At this point newvar O should be 20 indicating 20 records have been read Stem variables newvar 1 newvar 2 through newvar 20 will contain the 20 records that were read RRR e k ek e RRR RAR R EERE k REIKI KERIKERI KEK IK KKK AK KK kk k k kkk kkk SAY Uo ee oe EN ee ere Sole See joer Se ee See bee be u SAY newvar 0 records have been read from samplel data SAY DO i 1 TO newvar 0 Loop through all records x SAY newvar i Display the ith record x END EXECIO newvar O DISKW myoutdd STEM newvar Write exactly the number of records read Figure 12 7 EXECIO Example 6 12 18 05 390 V1R2 0 TSO E REXX User s Guide EN ELSE DO EN IF Using EXECIO to Process Information r EXECIO Example 6 continued IF rc 0 THEN If write wa
104. IN STEP MVSBACH START 88167 0826 STEP MVSBACH STOP 88167 0826 CPU OMIN 00 16SEC SRB JOB USERIDA START 88167 0826 JOB USERIDA STOP 88167 0826 CPU OMIN 00 16SEC SRB Using the Data Stack in TSO E Background and MVS Batch When an exec runs in the TSO E background or MVS batch it has the same use of the data stack as an exec that runs in the TSO E foreground The PULL instruction however works differently when the data stack is empty In the TSO E foreground PULL goes to the terminal for input In the TSO E background and MVS batch PULL goes to the input stream as defined by ddname SYSTSIN When SYSTSIN has no data the PULL instruction returns a null If the input stream has no data and the PULL instruction is in a loop the exec can result in an infinite loop 13 10 05 390 V1R2 0 TSO E REXX User s Guide Summary of TSO E Background and MVS Batch Summary of TSO E Background and MVS Batch CAPABILITIES TSO E BACKGROUND IKJEFT01 MVS BATCH IRXJCL Execs run without terminal interaction Execs run without terminal interaction Execs can contain e REXX instructions Built in functions TSO E REXX commands TSO E commands e TSO E external functions Execs can contain e REXX instructions e Built in functions e TSO E REXX commands e The TSO E external functions STORAGE and SETLANG Execs are invoked through the PARM parameter on the EXEC statement and through explicit o
105. Inner inner END END 2 Now what happens when the LEAVE instruction is added DO outer 1 TO 3 SAY Write a blank line DO inner 1 TO 3 IF inner 2 THEN LEAVE inner ELSE SAY Outer outer Inner inner END END ANSWERS 1 When this example runs you see on your screen the following Dm gt Outer 1 Inner 1 Outer 1 Inner 2 Outer 1 Inner 3 Outer 2 Inner 1 Outer 2 Inner 2 Outer 2 Inner 3 Outer 3 Inner 1 Outer 3 Inner 2 Outer 3 Inner 3 2 The result is one line of output for each of the inner loops Outer 1 Inner 1 Outer 2 Inner 1 Outer 3 Inner 1 Chapter 4 Controlling the Flow Within an Exec 4 19 Using Interrupt Instructions Using Interrupt Instructions Instructions that interrupt the flow of an exec can cause the exec to Terminate EXIT e Skip to another part of the exec marked by a label SIGNAL Go temporarily to a subroutine either within the exec or outside the exec CALL RETURN EXIT Instruction The EXIT instruction causes an exec to unconditionally end and return to where the exec was invoked If the exec was initiated from the PROC section of an ISPF selection panel EXIT returns to the ISPF panel If the exec was called by a program such as another exec EXIT returns to the program More about calling external routines appears later in this chapter and in Chapter 6 Writing Subroutines and Functions on page 6 1 In addition to ending an exec EXIT can also retur
106. Instruction RR RR RRR EERE RRR kkk kkkkkkkkkkkkxk REX KX RR RRR RK RR KKK KERR k k kk kkk k ERE RR This exec uses a PROCEDURE instruction to protect the variables within its function x RR RR RRR RR ke deje KERIKERI k k k k kk e ERIK KEI k KKK EK KKK kk k kk REE RE numberl 10 SAY pass number2 Displays 7 NUMBER2 EXIT pass PROCEDURE numberl 7 number2 5 RETURN number1 r Example Without the PROCEDURE Instruction kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR RR KK KERR RR kkk kkk kkk kk This exec does not use a PROCEDURE instruction to protect the variables within its function x RR kk RRR RRR ke kek k k e e kk e ke k k kk k k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k kk k kkk kk numberl 10 SAY pass number displays 7 5 EXIT pass numberl 7 number2 5 RETURN number1 Exposing Variables with PROCEDURE EXPOSE To protect all but specific variables use the EXPOSE option with the PROCEDURE instruction followed by the variables that are to remain exposed to the function r Example Using PROCEDURE EXPOSE RR kk RRR REE REE RR RRR ERR REE kk K k REXX KR RK KKK KR RE A K KKK KR REAR k k ERE RE This exec uses a PROCEDURE instruction with the EXPOSE option tox expose one variable numberl in its function RR RRR RRR RRR EER R RE e kke KEK kk k k k k kk KIKI KK RE AA KKK IA k k k kk kkk k kkk kk numberl 10 SAY pass
107. N To read a specific number of lines put the number immediately following the EXECIO command EXECIO 25 To read the entire data set put an asterisk immediately following the EXECIO command EXECIO When all the information is on the data stack either queue a null line to indicate the end of the information or if there are null lines throughout the data assign the Chapter 12 Processing Data and Input Output Processing 12 3 Using EXECIO to Process Information built in QUEUED function to a variable to indicate the number of items on the stack How to read the data set Depending on the purpose you have for the input data set use either the DISKR or DISKRU operand e DISKR Reading Only To initiate I O from a data set that you want to read only use the DISKR operand with the FINIS option The FINIS option closes the data set after the information is read Closing the data set allows other execs to access the data set and the ddname EXECIO DISKR FINIS Note Do not use the FINIS option if you want the next EXECIO statement in your exec to continue reading at the line immediately following the last line read e DISKRU Reading and Updating To initiate I O to a data set that you want to both read and update use the DISKRU operand without the FINIS option Because you can update only the last line that was read you usually read and update a data set one line ata time or go immediately
108. N lunch cost increased SAY Today s lunch cost more than yesterday s ELSE lunch cost remained the same or decreased SAY Today s lunch cost the same or less than yesterday s Exercises Using Comparison Expressions 1 In the preceding example of using a comparison expression what appears on the screen when you respond to the prompts with the following lunch costs Yesterday s Today s Lunch Lunch 4 42 3 75 3 50 3 50 3 75 4 42 2 What is the result 0 or 1 of the following expressions a Apples Oranges b Apples Apples c Apples Apples d e 100 1E2 100 1E2 f 100 1E2 ANSWERS 1 The following sentences appear a Today s lunch cost the same or less than yesterday s b Today s lunch cost the same or less than yesterday s c Today s lunch cost more than yesterday s 2 The expressions result in the following Remember 0 is false and 1 is true 0 The first Apples has a space sh 0 e o Op O O0 Chapter 3 Using Variables and Expressions 3 9 Using Expressions Logical Boolean Operators Logical expressions like comparison expressions return a true 1 or false 0 value when processed Logical operators combine two comparisons and return the true 1 or false 0 value depending on the results of the comparisons The logical operators are Operator amp amp amp Prefix Meaning AND Returns 1 if both comparisons are true
109. NAME MEMBER DISP SHR CLISTs can receive positional keyword and keyword value parameters ARG PARSE ARG PARSE UPPER ARG instructions arg dsname member disp An exec receives positional parameters Use the PARSE ARG and PARSE UPPER ARG instructions to receive keywords for example my data member member1 disp old parse upper arg dsname parse upper arg MEMBER mem parse upper arg DISP disp Recognizing comments within a parameter Recognizing comments within a parameter A CLIST PROC statement recognizes a comment within a parameter sent by the EXEC command and ignores that comment An ARG instruction does not recognize a comment within a parameter sent by the EXEC command It is treated as part of the argument Sending parameters to a CLIST Sending arguments to an exec EXEC command EXEC MY CLIST NEW MY DATA MEMBER MEMBER1 DISP OLD EXEC command from TSO E READY EXEC MY EXEC NEW my data member memberl disp old EXEC Sending information to a subprocedure Sending information to a subroutine SYSCALL statement SYSCALL SOMESUB amp VAR CALL instruction call somsub var Appendix C Comparisons Between CLIST and REXX C 5 CLIST REXX Sending information from a subprocedure Sending information from a subroutine RETURN statement SYSCALL SOMESUB amp VAR SET ANSWER amp LASTCC END SOMESUB PROC 1 V1 RETURN CODE 33
110. O E commands For more information see TSO E REXX Reference SC28 1975 10 6 0os 390 V1R2 0 TSO E REXX User s Guide TSO E External Functions Using the PROMPT Function When your profile allows for prompting the PROMPT function can set the prompting option on or off for interactive TSO E commands or it can return the type of prompting previously set When prompting is on execs can issue TSO E commands that prompt the user for missing operands The PROMPT function can be used only in REXX execs that run in the TSO E address space To set the prompting option on use the PROMPT function followed by the word ON enclosed within parentheses x PROMPT ON x is set to the previous setting of prompt and sets the current setting to ON x To set prompting off substitute the word OFF for ON To find out if prompting is available for TSO E interactive commands use the PROMPT function followed by empty parentheses x PROMPT x is set to ON or OFF The PROMPT function overrides the NOPROMPT operand of the EXEC command but it cannot override a NOPROMPT operand in your TSO E profile To display your profile issue the PROFILE command To change a profile from NOPROMPT to PROMPT issue PROFILE PROMPT Using the SETLANG Function You can use the SETLANG function to determine the language in which REXX messages are currently being displayed and to optionally change the language If you do not specify an argum
111. OC A 12 Execs can be stored in either sequential data sets or partitioned data sets PDSs A sequential data set contains only one exec while a PDS can contain one or more execs In a PDS each exec is a member and has a unique member name When a PDS consists entirely of execs it is called an exec library Exec libraries make execs easy to maintain and execute Your installation can keep commonly used execs in a system library and you can keep your own execs in a private exec library To learn important information about data sets at your installation use the Preliminary Checklist on page A 3 What is Allocation Before you can store execs in a data set you must create the data set by allocation Allocation can mean different things depending on your purpose In this book allocation means two things Creating a new data set in which to store REXX execs You can create a new data set with the ISPF PDF UTILITIES option or with the TSO E ALLOCATE command Checklists for creating a data set appear in Checklist 1 Creating and Editing a Data Set Using ISPF PDF on page A 5 Checklist 22 Creating a Data Set with the ALLOCATE Command on page A 9 Accessing an existing data set and associating it and possibly other data sets to a system file Allocating a data set to a system file SYSEXEC or SYSPROC enables you to execute the execs implicitly by simply typing their member names When more than one P
112. P IP Kerberos optional TCP IP Network Print Facility NPF TCP IP Network Print Facility NPF optional TCP IP OpenEdition Applications TCP IP OpenEdition Applications optional e TCP IP OS 2 Offload e TCP IP OS 2 Offload optional TIOC R1 TIOC base Time Sharing Option Extensions TSO E V2R5 TSO E base VisualLift for MVS V1R1 1 VisualLift Run Time Environment RTE base VisualLift Application Development optional Environment ADE VTAM V4R3 with the AnyNet feature VTAM base XVi 0OS 390 V1R2 0 TSO E REXX User s Guide Summary of Changes Changes to SC28 1974 00 for OS 390 Release 2 This book contains information previously presented in TSO E Version 2 REXX MVS User s Guide SC28 1882 which supports TSO Extensions for MVS This book includes terminology maintenance and editorial changes Technical changes or additions to the text and illustrations are indicated by a vertical line to the left of the change Copyright IBM Corp 1988 1996 xvii xviii OS 390 V1R2 0 TSO E REXX User s Guide Part 1 PART Learning the REXX Language The REXX language is a versatile general purpose programming language that can be used by new and experienced programmers This part of the book is for programmers who want to learn the REXX language The chapters in this part cover the following topics Chapter 1 Introduction The REXX language has many features that make it a powerful programming tool Chap
113. PUSH QUEUE or a combination of the two Chapter 11 Storing Information in the Data Stack 11 3 Manipulating the Data Stack ANSWER Possible Solution 1 RR RR RRR EERE RR ERR RRR RIK KERRIER REXX RRR RRR kkk k kkk kk kkk kkk k ER ERR This exec uses the PUSH instruction to put the letters T S 0 E on the data stack in reverse order RR kk RRR RRR RRR ERR R ERIK KERIKERI KERIB KKK AK KKK IKK k kk kk KERR PUSH E BRRKRRKEKRKERKEKEREREKEREEEKE PUSH 0 Data in stack is x PUSH S fourth push T x PUSH T third push S second push 0 x number QUEUED first push E x DO number kk kkk kkk ERR kkk kkk kkk kkk kkk PULL stackitem SAY stackitem END Possible Solution 2 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX XK RRR RRR kkk kkk kkk kkk kkk kkk kk This exec uses the QUEUE instruction to put the letters T S 0 E on the data stack in that order RR kk RRR RRR REE kek k k k e k k e ke k k kk k k k e kk e k k KER IK KKK k KKK IK k k k kk kkk k EERE QUEUE T kkkkkkkkkkkkkkkkkkkkkkkk kx QUEUE S Data in stack is QUEUE 0 first queue T x QUEUE E second queue S third queue 0 x DO QUEUED fourth queue E PULL stackitem RRR kkk RR ERIK kkk kkk ERIE SAY stackitem END m Possible Solution 3 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR KKK kkk kk kkk RRR KERR RE This exec uses the PUSH and
114. R PULL causes the same result as PULL in that it changes character information to uppercase before assigning it to one or more variables ARG Instruction The ARG instruction takes information passed as arguments to an exec function or subroutine and puts it into one or more variable names Before character information is put into a variable name ARG changes it to uppercase When ARG is followed by more than one variable name it parses the information into the available variable names For example if an exec named USERID REXX EXEC QUOTE can receive arguments you can invoke the exec with the EXEC command and the three arguments as follows 7 4 OS 390 V1R2 0 TSO E REXX User s Guide Parsing Data EXEC rexx exec quote Knowledge is power exec The exec receives the arguments with the ARG instruction as follows ARG wordl word2 word3 wordl contains KNOWLEDGE word2 contains IS word3 contains POWER The PARSE ARG instruction assigns information without altering it to variable names PARSE ARG wordl word2 word3 wordl contains Knowledge word2 contains is word3 contains power PARSE UPPER ARG causes the same result as ARG in that it changes character information to uppercase before assigning it to one or more variables PARSE VAR Instruction The PARSE VAR instruction parses a specified variable into one or more variable names that follow it If the variable contains character i
115. R2 0 TSO E REXX User s Guide Using Interrupt Instructions CALL RETURN Instructions The CALL instruction interrupts the flow of an exec by passing control to an internal or external subroutine An internal subroutine is part of the calling exec An external subroutine is another exec The RETURN instruction returns control from a subroutine back to the calling exec and optionally returns a value When calling an internal subroutine CALL passes control to a label specified after the CALL keyword When the subroutine ends with the RETURN instruction the instructions following CALL are executed instruction s CALL subl gt instruction s EXIT sub1 instruction s RETURN __ When calling an external subroutine CALL passes control to the exec name that is specified after the CALL keyword When the external subroutine completes you can use the RETURN instruction to return to where you left off in the calling exec REXX EXEC MAIN instruction s CALL sub2 gt instruction s Y REXX EXEC SUB2 instruction s RETURN For more information about calling subroutines see Chapter 6 Writing Subroutines and Functions on page 6 1 Chapter 4 Controlling the Flow Within an Exec 4 21 Using Interrupt Instructions SIGNAL Instruction The SIGNAL instruction like CALL interrupts the normal flow of an exec and causes control to pass to a specified label
116. SAY The transfer was a success ELSE SAY The transfer was not a success r USERID MY CLIST RECEIVE PROC 1 amp VAR IF amp VAR THEN SET SUCCESS 100 ELSE SET SUCCESS 50 EXIT CODE amp SUCCESS 13 6 09 390 V1R2 0 TSO E REXX User s Guide Running Execs in a TSO E Address Space Running an Exec in the Background Execs run in the background are processed when higher priority programs are not using the system Background processing does not interfere with a person s use of the terminal You can run time consuming and low priority execs in the background or execs that do not require terminal interaction Running an exec in the background is the same as running a CLIST in the background The program IKJEFTO1 sets up a TSO E environment from which you can invoke execs and CLISTs and issue TSO E commands For example to run an exec named SETUP contained in a partitioned data set USERID MYREXX EXEC submit the following JCL r Example of JCL to Run an Exec in the Background USERIDA JOB ACCOUNT DEPT BLDG PROGRAMMER NAME CLASS J MSGCLASS C MSGLEVEL 1 1 TMP EXEC PGM IKJEFTO1 DYNAMNBR 30 REGION 4096K SYSEXEC DD DSN USERID MYREXX EXEC DISP SHR SYSTSPRT DD SYSOUT A SYSTSIN DD SETUP The EXEC statement defines the program as IKJEFT01 In a DD statement you can assign one or more PDSs to the SYSEXEC or SYSPROC system file The SYSTSPRT DD allows y
117. SET rexx exec FILE sysexec SHR REUSE This use of uppercase and lowercase is intended to make a distinction between words that are fixed and words that can vary It does not mean that you must type REXX instructions and TSO E commands with certain words in uppercase and others in lowercase Exercises Periodically you will find sections with exercises you can do to test your understanding of the information Answers to the exercises are included when appropriate Where to Find More Information Please see the OS 390 Information Roadmap GC28 1727 for an overview on the documentation associated with OS 390 Referenced Program Products This book refers to the following products e REXX Compiler for REXX 370 Program Number 5695 013 REXX Library for REXX 370 Program Number 5695 014 X V 0S 390 V1R2 0 TSO E REXX User s Guide Elements in OS 390 You can use the following table to see the relationship of a product you are familiar with and how it is referred to in OS 390 Release 2 OS 390 Release 2 is made up of elements and features that contain function at or beyond the release level of the products listed in the following table The table gives the name and level of each product on which an OS 390 element or feature is based identifies the OS 390 name of the element or feature and indicates whether it is part of the base or optional For more compatibility information about OS 390 elements see OS 390 Up and Running
118. SO E and Other MVS Address Spaces 13 11 Defining Language Processor Environments Defining Language Processor Environments Before an exec can be processed a language processor environment must exist A language processor environment defines the way a REXX exec is processed and how it accesses system services Because MVS contains different types of address spaces and each one accesses services a different way REXX in TSO E provides three default parameters modules that define language processor environments They are e IRXTSPRM for TSO E e IRXPARMS for non TSO E e IRXISPRM for ISPF The defaults are set by TSO E but they can be modified by a system programmer What is a Language Processor Environment A language processor environment defines characteristics such as e The search order used to locate commands and external routines The ddnames for reading and writing data and from which execs are loaded The valid host command environments and the routines that process commands in each host command environment e The function packages user local and system that are available in the environment and the entries in each package Whether execs running in the environment can use the data stack e The names of routines that handle system services such as I O operations loading of an exec obtaining and freeing storage and data stack requests Note A language processor environment is different from a host comma
119. SYSVAR sysproc The SYSVAR function can be used only in REXX execs that run in the TSO E address space Many of the SYSVAR arguments retrieve the same information as do CLIST control variables The following tables divide the argument values into categories pertaining to user terminal language exec system and console session information User Information Argument Value Description SYSPREF Prefix as defined in user profile SYSPROC Logon procedure of current session SYSUID User ID of current session 10 10 05 390 V1R2 0 TSO E REXX User s Guide TSO E External Functions Terminal Information Argument Value Description SYSLTERM Number of lines available on screen SYSWTERM Width of screen Language Information Argument Value Description SYSPLANG Primary language for translated messages SYSSLANG Secondary language for translated messages SYSDTERM Whether DBCS is supported for this terminal SYSKTERM Whether Katakana is supported for this terminal Exec Information Argument Value Description System Information SYSENV Whether exec is running in foreground or background SYSICMD Name by which exec was implicitly invoked SYSISPF Whether ISPF is available for exec SYSNEST Whether exec was invoked from another exec or CLIST Invocation could be implicit or explicit SYSPCMD Name of most rece
120. TRAP 100 OUTTRAP external function x OUTTRAP var 100 CONTROL statement CONTROL PROMPT PROMPT external function x PROMPT on amp SYSDSN built in function IF amp SYSDSN SYSI MYLIB OK THEN SYSDSN external function IF SYSDSN SYS1 MYLIB OK THEN Control Variables For User Information amp SYSPREF WRITE amp SYSPREF amp SYSPROC amp SYSUID For Terminal Information amp SYSLTERM amp SYSWTERM For CLIST Information amp SYSENV amp SYSICMD amp SYSISPF amp SYSNEST amp SYSPCMD amp SYSSCMD For System Information amp SYSCPU amp SYSHSM amp SYSJES amp SYSLRACF amp SYSNODE amp SYSRACF amp SYSSRV amp SYSTERMID amp SYSTSOE Arguments of the SYSVAR external function For User Information SYSPREF SAY SYSVAR syspref SYSPROC SYSUID For Terminal Information SYSLTERM SYSWTERM For Exec Information SYSENV SYSICM SYSISP SYSNES SYSPCM SYSSCMD oA To For System Information SYSCPU SYSHSM SYSJES SYSLRACF SYSNODE SYSRACF SYSSRV SYSTERMID SYSTSOE C 2 08 390 V1R2 0 TSO E REXX User s Guide CLIST REXX Control Variables For System Information Arguments of the MVSVAR external function For System Information amp SYSAPPCLU SYSAPPCLU amp SYSDFP SYSDFP amp SYSMVS SYSMVS amp SYSNAME SYSNAME amp SYSSECLAB SYSSECLAB amp SYSSMFID SYSSMFID amp SYSSMS SYSSMS amp SYSCLONE SYSCLONE am
121. The first MAKEBUF creates buffer 1 the second creates buffer 2 and so on For example if an exec issued three MAKEBUF commands that created three buffers when you issue DROPBUF 2 the second and third buffers and all elements within them are removed To remove all elements from the entire data stack including elements placed on the data stack before buffers were added issue DROPBUF 0 DROPBUF 0 creates an empty data stack and should be used with caution Note When an element is removed below a buffer the buffer disappears Thus when elements are unintentionally removed below a buffer the corresponding DROPBUF command might remove the incorrect buffer and its elements To prevent an exec from removing elements below a buffer use the QUEUED built in function or use the NEWSTACK command as described in Protecting Elements in the Data Stack on page 11 14 Finding the Number of Buffers with the QBUF Command To find out how many buffers were created with the MAKEBUF command use the TSO E REXX QBUF command QBUF returns in the REXX special variable RC the number of buffers created MAKEBUF MAKEBUF QBUF SAY The number of buffers is RC RC 2 QBUF returns the total number of buffers created not just the ones created by a single exec Thus if an exec issued two MAKEBUF commands and called a routine that issued two more when the routine issues a QBUF command RC returns the total number of buffers created which
122. These alphabetic characters can be from within an exec such as words in a REXX instruction or they can be external to an exec and processed as input You can prevent this translation to uppercase in two ways depending on whether the characters are read as parts of instructions from within an exec or are read as input to an exec 2 14 09 390 V1R2 0 TSO E REXX User s Guide Preventing Translation to Uppercase From Within an Exec To prevent translation of alphabetic characters to uppercase from within an exec simply enclose the characters in single or double quotation marks Numbers and special characters whether or not in quotation marks are not changed by the language processor For example when you follow a SAY instruction with a phrase containing a mixture of alphabetic characters numbers and special characters only the alphabetic characters are changed SAY The bill for lunch comes to 123 51 results in THE BILL FOR LUNCH COMES TO 123 51 Quotation marks ensure that information from within an exec is processed exactly as typed This is important in the following situations For output when it must be lowercase or a mixture of uppercase and lowercase To ensure that commands are processed correctly For example if a variable name in an exec is the same as a command name the exec ends in error when the command is issued It is good programming practice to avoid using variable names that are the same as commands but j
123. U 10 5 SYSCLONE 10 5 SYSCPU 10 11 SYSCPUS external function 10 8 SYSDFP 10 5 SYSDSN external function 10 9 SYSDTERM 10 11 SYSENV 10 11 SYSEXEC 2 12 13 4 allocating to A 10 SYSEXEC system file reason to allocate to 13 4 SYSHSM 10 11 SYSICMD 10 11 SYSISPF 10 11 SYSJES 10 11 SYSKTERM 10 11 SYSLRACF 10 11 SYSLTERM 10 11 SYSMVS 10 5 SYSNAME 10 5 SYSNEST 10 11 SYSNODE 10 11 SYSPCMD 10 11 SYSPLANG 10 11 SYSPLEX 10 5 SYSPREF 10 10 SYSPROC 2 8 2 12 10 10 13 4 allocating to A 12 SYSPROC system file reason to allocate to 13 4 SYSRACF 10 11 SYSSCMD 10 11 SYSSECLAB 10 5 SYSSLANG 10 11 SYSSMFID 10 5 SYSSMS 10 5 SYSSRV 10 11 system file allocating to 2 12 13 4 A 1 reason to allocate to 13 4 SYSEXEC 2 12 13 4 B 1 SYSPROC 2 8 2 12 13 4 B 1 SYSUEXEC B 1 SYSUPROC B 1 Systems Application Architecture SAA See also SAA Systems Application Architecture Procedures Language xiii SYSTERMID 10 11 SYSTSOE 10 11 SYSUEXEC B 1 Index X 9 SYSUID 10 10 SYSUPROC B 1 SYSVAR external function 10 10 SYSWTERM 10 11 T template 7 6 trace See interactive debug facility TRACE instruction 9 2 ending tracing 9 8 interactive tracing 9 4 tracing operation 3 14 tracing result 3 15 TSO host command environment 8 6 TSO E background comparison to MVS batch 13 11 using the data stack 13 10 TSO E commands ALLOCATE A 9 A 10 A 12 ALTLIB B 1 EXEC 2 11 2 17 11 16 prompt option 8 4 with data se
124. UEUE B QUEUE C QELEM SAY RC 2 Given the data stack below and the instructions that created it what are the results of the subsequent instructions that follow MAKEBUF 3 data item MAKEBUF 2 prompt MAKEBUF 1 MAKEBUF QUEUE prompt MAKEBUF QUEUE data QUEUE info QUEUE item MAKEBUF a What is returned to the function SAY QUEUED b What is RC QBUF SAY RC c What is RC QELEM SAY RC Chapter 11 Storing Information in the Data Stack 11 13 Protecting Elements in the Data Stack d What are both RCs and the result of the QUEUED function DROPBUF 2 QBUF SAY RC QELEM SAY RC SAY QUEUED ANSWERS 1 a C b b c B bwas changed to uppercase because it was queued without quotes and pulled without PARSE d 2 e 1 f 0 2 a 4 b 3 c 0 d 1 1 1 Protecting Elements in the Data Stack In certain environments particularly MVS where multiple tasks run at the same time it is often important for an exec to isolate stack elements from other execs Similarly an exec in TSO E might want to protect stack elements from a routine subroutine or function that it calls For example if an exec puts elements on the data stack for its own use and then calls a subroutine that issues an interactive TSO E command such as ALLOCATE the command goes to the data stack first for input to the command Because the stack input is incorrect f
125. VS PARSE ARG input SAY input DATA start DO UNTIL DATA PARSE PULL data pull data from the input stream SAY data END RRR k k k ke ek ke e e k e e k k k k ek k IK k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k kkk kk kkk Now use EXECIO to write a timestamp to the sequential data set that was allocated to the OUTDD file by the JCL x used to invoke this exec E e k e ke ke eke ke e e e e e k k k k e k k k ke k k k KEI kk k k k k KEK k k kk k k k k kk k k k k kk k kkk kk kkk OUTLINE 1 Exec JCLTEST has ended at TIME EXECIO 1 DISKW OUTDD STEM OUTLINE FINIS Write the line SAY Leaving exec JCLTEST EXIT 137 send a condition code of 137 x m USERID TRACE OUTPUT Exec JCLTEST has ended at 15 03 06 Chapter 13 Using REXX in TSO E and Other MVS Address Spaces 13 9 Running Execs in a Non TSO E Address Space r USERID IRXJCL OUTPUT Running exec JCLTEST Test IRXJCL First line of data Second line of data Third line of data Leaving exec JCLTEST Segment of Output from the JCL Listing ALLOC FOR USERIDA MVSBACH 224 ALLOCATED TO OUTDD 954 ALLOCATED TO SYSTSPRT 7E0 ALLOCATED TO SYSEXEC JES2 ALLOCATED TO SYSTSIN USERIDA MVSBACH STEP WAS EXECUTED COND CODE 0137 USERID TRACE OUTPUT KEPT VOL SER NOS TS0032 USERID IRXJCL OUTPUT KEPT VOL SER NOS TS0032 USERID MYREXX EXEC KEPT VOL SER NOS TS0001 JES2 J0B28359 10000101 SYS
126. When you issue the NEWSTACK it is your responsibility to issue a corresponding DELSTACK command All elements added to the data stack after the NEWSTACK command are placed in the new data stack The original stack contains the elements placed on the stack before the NEWSTACK command Original New Stack Stack Chapter 11 Storing Information in the Data Stack 11 15 Protecting Elements in the Data Stack Instructions that could be used to create the illustrated new stack are as follows PUSH oldA PUSH oldl NEWSTACK QUEUE newY PUSH newX In the Example of an Interactive Command Error the MAKEBUF command did not protect the elements in the stack If you substitute the NEWSTACK command for the MAKEBUF command the elements become inaccessible r Example of using NEWSTACK with an Interactive Command EXECI PUSH prompti PUSH prompt2 CALL subl EXIT SUB1 NEWSTACK ALLOCATE Note To have an interactive command prompt the user for input from the terminal run an exec explicitly with the EXEC command and specify prompt or include the PROMPT on function within the exec For more information see Causing Interactive Commands to Prompt the User on page 8 4 Deleting a Private Stack with the DELSTACK Command When an exec wants to delete the new stack and remove all elements placed on the new stack it can issue the TSO E REXX DELSTACK command The DELSTACK command removes the most recently create
127. XX FR RRR RRR k kk k RRR RAR RRR pa 1 ma 1 kids 3 SAY There are pa ma kids people in this family 2 What is the value of a 6 4 1 b 6 44 1 c 6 4 2 d 6 4 2 e 2496 5 2 ANSWERS 1 There are 5 people in this family 2 The values are as follows a 3 b 1 c 26 d 36 e 2 Comparison Operators Expressions that use comparison operators do not return a number value as do arithmetic expressions Comparison expressions return either a true or false response in terms of 1 or 0 as follows 1 True 0 False Comparison operators can compare numbers or strings and ask questions such as Are the terms equal A B Is the first term greater than the second A B Is the first term less than the second A B For example if A 4 and B 3 then the results of the previous comparison questions are A B Does 4 3 0 False A gt B Ils 4 3 1 True A lt B Is4 3 0 False Chapter 3 Using Variables and Expressions 3 7 Using Expressions The more commonly used comparison operators are as follows Operator Meaning Strictly Equal Equal Not strictly equal Not equal gt Greater than lt Less than gt lt Greater than or less than same as not equal gt Greater than or equal to lt Not less than lt Less than or equal to gt Not greater than Note The not character is synonymous with the backslash The two characters may be us
128. XX literal string SAY This is a REXX literal string SAY This AS ra REXX Titeral string SAY This is a REXX literal string SAY This is a REXX literal string SAY This is a REXX literal string When the example runs you see six lines of identical output on your screen followed by one indented line E This is a REXX literal string This is a REXX literal string This is a REXX literal string This is a REXX literal string This is a REXX literal string is a REXX literal string a a a This is a REXX literal string a a S Thus you can begin an instruction anywhere on a line you can insert blank lines and you can insert extra spaces between words in an instruction because the language processor ignores blank lines and spaces that are greater than one This flexibility of format allows you to insert blank lines and spaces to make an exec easier to read Only when words are parsed do blanks and spaces take on significance More about parsing is covered in Parsing Data on page 7 4 Types of REXX Instructions There are five types of REXX instructions keyword assignment label null and command The following example is an ISPF PDF Edit panel that shows an exec with various types of instructions A description of each type of instruction appears after the example In most of the descriptions you will see an edit line number without the prefixed zeroes to help you locate th
129. age lt status OTHERWISE IF sex status ELSE status END under 5 female 5 to 12 male 5 to 12 ERS 13 through 19 Using Conditional Instructions r Example Using SELECT WHEN OTHERWISE END kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR RRR KR KER kkk kkk kkk ERE kk This exec receives input with a person s age and sex In reply it displays a person s status as follows female 20 and up male 20 and up 5 THEN BABY 13 THEN M THEN us BOY us GIRL 20 THEN TEENAGER M THEN MAN WOMAN SAY This person should be counted as a status person younger than 5 person between 5 and 12 boy between 5 and 12 girl between 5 and 12 person between 13 and 19 man 20 or older woman 20 or older EK kk k k k e ek e ke k k kk k k k ke kk e k k k kk k k k k kk k IK ERIK k kk k k k k kk k k k k kk kkk k kkk kk PARSE ARG age sex Each SELECT must end with an END Indenting each WHEN makes an exec easier to read Exercises Using the SELECT WHEN OTHERWISE END Instruction Thirty days hath September April June and November all the rest have thirty one save February alone Write an exec that provides the number of days in a month First have the exec ask the user for a month specified as a number from 1 to 12 with January being 1 February 2 and so forth Then
130. ages System packages Functions written for system wide use such as the TSO E external functions System packages are searched after user and local packages Function packages written by a user or an installation must be pre loaded at logon time The default name for the user packages is IRXFUSER and the default name for the local package is IRXFLOC Other function packages can be named in a parameter block set up by a system programmer For more information about function packages see TSO E REXX Reference SC28 1975 Search Order for Functions When the language processor encounters a function call if defaults have not been changed it goes through the following search order e Internal functions Labels in the exec that issued the function call are searched first unless the label is in quotation marks in the function call e Built in functions The built in functions are next in the search order e Function packages User local and system function packages in that order are searched Load libraries Functions stored in a load library are next in the search order External function An external function and its caller must either be members in the same PDS or members of PDSs allocated to a system library such as SYSEXEC or SYSPROC Chapter 10 Using TSO E External Functions 10 17 Function Packages 10 18 05 390 V1R2 0 TSO E REXX User s Guide What is a Data Stack Chapter 11 Storing In
131. al When the data stack is empty PULL removes information from the terminal PULL and PARSE PULL remove one element from the top of the data stack PULL stackitem Using the examples from Adding Elements to the Data Stack on page 11 2 the variable stackitem then contains the value of elem1 with the characters translated to uppercase SAY stackitem displays STRING 1 FOR THE DATA STACK When you add PARSE to the preceding instruction the value is not translated to uppercase PARSE PULL stackitem SAY stackitem displays String 1 for the data stack After either of the preceding examples the data stack appears as follows PULL elemA Determining the Number of Elements on the Stack The QUEUED built in function returns the total number of elements on a data stack For example to find out how many elements are on the data stack you can use the QUEUED function with no arguments SAY QUEUED displays a decimal number To remove all elements from a data stack and display them you can use the QUEUED function as follows number QUEUED DO number PULL element SAY element END Exercise Using the Data Stack Write an exec that puts the letters T S O E on the data stack in such a way that they spell TSOE when removed Use the QUEUED built in function and the PULL and SAY instructions to help remove the letters and display them To put the letters on the stack you can use the REXX instructions
132. ally filled I O buffers to the data set EXECIO DISKW myoutdd FINIS e STEM To write the information from compound variables or a list of variables beginning with the name specified after the STEM keyword The variables instead of the data stack holds the information to be written EXECIO DISKW myoutdd STEM newvar In this example the variables would have the stem newvar and lines of information from the compound variables would go to the data set Each variable is labeled newvar 1 newvar 2 newvar 3 and so forth The variable newvar 0 is not used when writing from compound variables When is specified with a stem the EXECIO command stops writing information to the data set when it finds a null value or an uninitialized compound variable In this case if the list contained 10 compound variables the EXECIO command stops at newvar 11 The EXECIO command can also specify the number of lines to write from a list of compound variables EXECIO 5 DISKW myoutdd STEM newvar In this example the EXECIO command writes 5 items from the newvar variables including uninitialized compound variables if any See EXECIO Example 6 under the heading Figure 12 7 on page 12 18 which shows the usage of the EXECIO command with stem variables Return Codes from EXECIO After an EXECIO command runs it sets the REXX special variable RC to a return code Valid return codes from EXECIO are Return Code Meaning 0 Normal compl
133. arameter of the EXEC statement Two arguments TEST and IRXJCL follow the member name Output from the exec goes to an output data set named USERID IRXJCL OUTPUT which is specified in the SYSTSPRT DD statement The SYSTSIN DD statement supplies the exec with three lines of data in the input stream This exec also uses EXECIO to write a 1 line timestamp to the end of the sequential data set USERID TRACE OUTPUT which is allocated in the OUTDD statement 13 8 05 390 V1R2 0 TSO E REXX User s Guide Running Execs in a Non TSO E Address Space r USERID JCL EXEC USERIDA JOB ACCOUNT DEPT BLDG PROGRAMMER NAME CLASS J MSGCLASS H MSGLEVEL 1 1 MVSBACH EXEC PGM IRXJCL PARM JCLTEST Test IRXJCL ei Name of exec PNE gt Argument POE gt OUTDD DD DSN USERID TRACE OUTPUT DISP MOD SYSTSPRT DD DSN USERID IRXJCL OUTPUT DISP OLD SYSEXEC DD DSN USERID MYREXX EXEC DISP SHR SYSTSIN DD First line of data Second line of data Third line of data m USERID MYREXX EXEC JCLTEST kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR KERR kk kkk kkk kkk kkk kkk kkk kkk This exec receives input from its invocation in JCL EXEC pulls data from the input stream and sends back a condition code of 137 x RRR RRR ke ek ke e ke k e e k k k k eek dee k k k k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k kkk kk kkk TRACE error SAY Running exec JCLTEST ADDRESS M
134. are no other data sets allocated to SYSEXEC specify your PDS only Your SETUP exec could look like the following example kkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX KR KKK A A KA AK k Ek ARR k Kk K A k k kk kkk This exec is an example of how to allocate a private PDS named USERID REXX EXEC to the beginning of a concatenation to SYSEXEC that consists of one other data set named ISP PHONE EXEC To make sure that SYSEXEC is available the exec issues EXECUTIL SEARCHDD yes command After the ALLOCATE command executes a message indicates whether the command was successful or not x FORK KKK je eee eee dede jede e e e k k K k eee eee KEI kk k k k k kk k k IKKE EXECUTIL SEARCHDD yes to ensure that SYSEXEC is available ALLOC FILE SYSEXEC DATASET rexx exec isp phone exec SHR REUSE IF RC 0 THEN SAY Allocation to SYSEXEC completed ELSE SAY Allocation to SYSEXEC failed Note The order in which you list data sets in an ALLOCATE command is the order in which they are concatenated and searched To give your execs priority in the search order list your data set of execs before other data sets Generally all the data sets in the list should have the same record format either RECFM VB or RECFM FB and logical record length LRECL Also the first data set in the list can determine the block size BLKSIZE for the data sets that follow If the block size of the first data set is smaller than the blo
135. are the answers to the following examples a 22 12 1 b 6 2 gt 45 7 2 1 c 10 2 5 1 5 2 15 1 2 In the example of the student and the college from Exercises Using Logical Expressions on page 3 11 if the parentheses were removed from the student s formula what would be the outcome for the college IF inexpensive scholarship amp reputable nearby THEN SAY I ll consider it ELSE SAY Forget it Remember the college is inexpensive did not offer a scholarship is reputable but is 1000 miles away ANSWERS 1 The results are as follows a 34 22 12 34 b 1 true 323 1 c 32 20 2 15 1 2 I ll consider it The amp operator has priority as follows but the outcome is the same as the previous version with the parentheses IF inexpensive scholarship amp reputable nearby THEN __ true false true false false true true Tracing Expressions with the TRACE Instruction You can use the TRACE instruction to display how the language processor evaluates each operation of an expression as it reads it or to display the final result of an expression These two types of tracing are useful for debugging execs Tracing Operations To trace operations within an expression use the TRACE TRACE Intermediates form of the TRACE instruction All expressions that follow the instruction are then broken down by operation and analyzed as gt V gt
136. are three keywords that work together in one instruction Each keyword forms a clause which is a subset of an instruction If the expression that follows the IF keyword is true the instruction that follows the THEN keyword is processed Otherwise the instruction that follows the ELSE keyword is processed If more than one instruction follows a THEN or an ELSE the instructions are preceded by a DO line 14 and followed by an END line 17 More information about the IF THEN ELSE instruction appears in Using Conditional Instructions on page 4 2 The EXIT keyword line 19 tells the language processor to end the exec Using EXIT in the preceding example is a convention not a necessity because processing ends automatically when there are no more instructions in the exec More about EXIT appears in EXIT Instruction on page 4 20 Assignment An assignment gives a value to a variable or changes the current value of a variable A simple assignment instruction is number 4 Chapter 2 Writing and Running a REXX Exec 2 7 Syntax of REXX Instructions In addition to giving a variable a straightforward value an assignment instruction can also give a variable the result of an expression An expression is something that needs to be calculated such as an arithmetic expression The expression can contain numbers variables or both number 4 4 number number 4 In the first of the two examples the value of number is 8 If the second
137. array and retrieved by number An array is an arrangement of elements in one or more dimensions identified by a single name You could have an array called employee that contains names as follows EMPLOYEE 1 Adams Joe 2 Crandall Amy 3 Devon David 4 Garrison Donna 5 Leone Mary 6 Sebastian Isaac In some computer languages you access an element in the array by the number of the element such as employee 1 which retrieves Adams Joe In REXX you use compound variables What is a Compound Variable Compound variables are a way to create a one dimensional array or a list of variables in REXX Subscripts do not necessarily have to be numeric A compound variable contains at least one period with characters on both sides of it The following are examples of compound variables FRED 5 Array Row Col employee name phone Copyright IBM Corp 1988 1996 7 1 Using Compound Variables and Stems The first variable in a compound variable always remains a symbol with no substitution The remaining variables in a compound variable take on values previously assigned If no value was previously assigned the variable takes on the uppercase value of the variable name first Fred last Higgins employee first last EMPLOYEE is assigned FIRST Higgins SAY employee first middle last Displays EMPLOYEE Fred MIDDLE Higgins You can use a DO loop to initialize a group of compound variables and set up an array
138. at links to modules on the same task level This environment allows you to pass multiple parameters to an invoked module and allows the invoked module to update the parameters The parameters you pass to the module do not include a length identifier ATTACH an environment that attaches modules on a different task level ATTCHMVS an environment that attaches modules on a different task level This environment allows you to pass multiple parameters to an invoked module and allows the invoked module to update the parameters The parameters you pass to the module include a length identifier ATTCHPGM an environment that attaches modules on a different task level This environment allows you to pass multiple parameters to an invoked module and allows the invoked module to update the parameters The parameters you pass to the module do not include a length identifier ISPEXEC the environment in which ISPF commands execute ISREDIT the environment in which ISPF PDF EDIT commands execute 8 6 05 390 V1R2 0 TSO E REXX User s Guide Issuing Other Types of Commands from an Exec CONSOLE the environment in which MVS system and subsystem commands execute To use the CONSOLE environment you must have TSO E CONSOLE command authority and an extended MCS console session must be active You use the TSO E CONSOLE command to activate an extended MCS console session See TSO E System Programming Command Reference SC28 1972 for more information a
139. ata Set into Compound Variables ALLOC DA old data F indd SHR REUSE EXECIO DISKR indd STEM newvar DO i 1 to newvar 0 SAY newvar i END When you want to copy a varying number of lines to compound variables you can use a variable within the EXECIO command as long as the variable is not within quotation marks For example the variable lines can represent the number of lines indicated when the exec is run r Copying a Varying Number of Lines into Compound Variables ARG lines ALLOC DA old data F indd SHR REUSE EXECIO lines DISKR indd STEM newvar Copying Information from Compound Variables to a Data Set To copy 10 compound variables with the stem newvar regardless of how many items are in the list write the following instructions Note An uninitialized compound variable will default to the value of its name For example if newvar 9 and newvar 10 do not contain values the data set will receive the values NEWVAR 9 and NEWVAR 10 r Copying from Compound Variables ALLOC DA new data F outdd LIKE old data NEW EXECIO 10 DISKW outdd STEM NEWVAR Updating Information in a Data Set You can update a single line of a data set with the EXECIO command or you can update multiple lines Use the DISKRU form of the EXECIO command to read information that you may subsequently update Note The line written must be the same length as the line read When a changed line is longe
140. ataset Give the first dataset allocated DO j i 1 TO ddlist 0 BY 2 WHILE done NO next j 1 IF next lt ddlist 0 amp words ddlist next 1 THEN done YES if we reach the end of the command output or the next DDNAME we are done x ELSE SAY ddlist j Give the next dataset allocated END END END If done NO then If the DDNAME is not allocated say The DDNAME ddname is not allocated Then say so EXIT 0 10 16 05 390 V1R2 0 TSO E REXX User s Guide Function Packages Function Packages A function package is a group of external routines functions and subroutines that are accessed more quickly than external routines written in interpreted REXX Routines in a function package must be written in a programming language that produces object code which can be link edited into a load module The routine must also support the system interface for function packages Some programming languages that meet these qualifications are assembler COBOL and PL I There are three types of function packages e User packages User written external functions that are available to an individual These functions are searched before other types of function packages and are often written to replace the other types of function packages Local packages Application or system support functions that are generally available to a specific group of users Local packages are searched after user pack
141. be updated SYSEXDATE Expiration date Year day format for example 1985 365 SYSPASSWORD Password indication NONE READ WRITE SYSRACFA RACF indication NONE GENERIC DISCRETE SYSUPDATED Change indicator YES NO SYSTRKSCYL Tracks per cylinder for the unit identified in the SYSUNIT variable SYSBLKSTRK Blocks per track for the unit identified in the SYSUNIT variable SYSADIRBLK Directory blocks allocated returned only for partitioned data sets when DIRECTORY is specified SYSUDIRBLK Directory blocks used returned only for partitioned data sets when DIRECTORY is specified SYSMEMBERS Number of members returned only for partitioned data sets when DIRECTORY is specified SYSREASON LISTDSI reason code SYSMSGLVL1 First level message if an error occurred SYSMSGLVL2 Second level message if an error occurred SYSDSSMS Information about the type of a data set provided by DFSMS MVS SYSDATACLASS SMS data class name SYSSTORCLASS SMS storage class name SYSMGMTCLASS SMS management class name Using the MSG Function The MSG function can control the display of TSO E messages When the MSG function is not used both error and non error messages are displayed as an exec runs These messages can interfere with output especially when the exec s output is a user interface such as a panel The MSG function can be used only in REXX execs that run in the TSO E address Space 10 4 os 390 V1R2 0 TSO E REXX User s Guide TSO E External
142. bout using the CONSOLE command CPICOMM the environment that allows you to invoke the SAA common programming interface CPI Communications calls LU62 the environment that allows you to invoke the APPC MVS calls that are based on the SNA LU 6 2 architecture These calls are referred to as APPC MVS calls throughout the book APPCMVS the environment that allows you to access MVS APPC callable services related to server facilities and for the testing of transaction programs In a non TSO E environment TSO E REXX provides the following host command environments MVS the initial host command environment LINK LINKMVS LINKPGM ATTACH e ATTCHMVS ATTCHPGM e CPICOMM e LU62 e APPCMVS From TSO E READY mode TSO E REXX provides the following host command environments e TSO the initial host command environment e MVS e LINK LINKMVS LINKPGM ATTACH ATTCHMVS ATTCHPGM CONSOLE CPICOMM e LU62 e APPCMVS In ISPF TSO E REXX provides the following host command environments e TSO the initial host command environment e MVS e LINK LINKMVS LINKPGM ATTACH Chapter 8 Entering Commands from an Exec 8 7 Issuing Other Types of Commands from an Exec ATTCHMVS ATTCHPGM SPEXEC e SREDIT e CONSOLE CPICOMM e LU62 e APPCMVS Note These lists of host command environments represent the defaults Your installation may have added or deleted environments The defaul
143. c 5 4 comparison 5 5 conversion 5 5 formatting 5 5 string manipulating 5 6 SUBSTR 6 2 C CALL RETURN instruction 4 21 6 3 character uppercase preventing with PARSE 2 15 2 18 preventing with quotation mark 2 15 checklist creating a data set with ALLOCATE A 9 creating and editing a data set using ISPF PDF A 5 preliminary A 3 writing an exec to allocate to SYSEXEC A 10 writing an exec to allocate to SYSPROC A 12 checklist 1 creating and editing a data set using ISPF PDF A 5 checklist 42 creating a data set with ALLOCATE A 9 checklist 43 writing an exec to allocate to SYSEXEC A 10 checklist 44 writing an exec to allocate to SYSPROC A 12 clause as a subset of an instruction 2 7 CLIST comparison to REXX C 1 invoking an exec 13 5 returning information to an exec 13 6 running from an exec 13 5 comma to continue an instruction 2 4 commands ALLOCATE A 9 A 10 A 12 ALTLIB B 1 as an instruction 2 8 CONSOLE 8 7 DELSTACK 11 16 DROPBUF 11 10 enclosing in quotation marks 2 15 8 2 EXEC 2 11 2 17 11 16 prompt option 8 4 with data set name as argument 8 2 EXECIO 12 3 EXECUTIL HI 4 10 EXECUTIL SEARCHDD 13 4 EXECUTIL TE 9 8 EXECUTIL TS 9 4 9 5 issuing from an exec 8 6 LISTALC STATUS A 3 LISTDS A 4 MAKEBUF 11 10 NEWSTACK 11 15 QBUF 11 11 QELEM 11 11 QSTACK 11 16 SUBCOM 8 11 TSO E REXX 8 1 comment beginning an exec 2 2 2 8 X 2 09 390 V1R2 0 TSO E REXX User s Guide comment continued distinguishing an exec from a
144. capabilities loss 1 2 Interpreted language aa 1 2 Extensive parsing capabilities sns 1 2 Components of REXX 2s 1 2 The SAA SGIULIOn 5254 Se iu ot cerises ra oes Ge uode d er essi S It 1 3 Benefits of Using a Compiler 2 200 220 0045 1 3 Improved Performance ees 1 4 Reduced System Load o u Sunc be YI Xu d 1 4 Protection for Source Code and Programs 1 4 Improved Productivity and Quality les 1 4 Portability of Compiled Programs s 1 4 SAA Compliance Checking 202000002 eee 1 5 This chapter describes the REXX programming language and some of its features What is REXX REXX is a programming language that is extremely versatile Aspects such as common programming structure readability and free format make it a good language for beginners and general users Yet because the REXX language can be intermixed with commands to different host environments provides powerful functions and has extensive mathematical capabilities it is also suitable for more experienced computer professionals The TSO E implementation of the REXX language allows REXX execs to run in any MVS address space You can write a REXX exec that includes TSO E services and run it in a TSO E address space or you can write an application in REXX to run outside of a TSO E address space For more information see Chapter 13
145. ce SC28 1975 Examples of whole numbers are 123456789 0 91221 999 12 5 A decimal number includes a decimal point Results of arithmetic operations with decimal numbers are limited to a total maximum of nine digits NUMERIC DIGITS default before and after the decimal Examples of decimal numbers are 123456 789 0 888888888 1 25E2 A floating point number in exponential notation is sometimes called scientific notation The number after the E represents the number of places the decimal point moves Thus 1 25E2 also written as 1 25E 2 moves the decimal point to the right two places and results in 125 When an E is followed by a minus the decimal point moves to the left For example 1 25E 2 is 0125 Floating point numbers are used to represent very large or very small numbers For more information about floating point numbers see TSO E REXX Reference SC28 1975 12 A signed number with a minus next to the number represents a negative value A plus next to a number indicates that the number should be processed as it is written When a number has no sign it is processed as a positive value 3 4 OS 390 V1R2 0 TSO E REXX User s Guide Using Expressions The arithmetic operators you can use are as follows Operator Meaning Add Subtract S Multiply Divide Divide and return a whole number without a remainder Il Divide and return the remainder only X Raise a number to a whole number power number Negate the
146. cing the function call with the value 6 18 0os 390 V1R2 0 TSO E REXX User s Guide Using Compound Variables and Stems Chapter 7 Manipulating Data Using Compound Variables and Stems 7 1 What is a Compound Variable 0 20000 0004 7 1 Using Stelms 2 5 e ege Rooks Haden di fa be Pe kee OSES o 7 2 Exercises Using Compound Variables and Stems 7 3 Parsing Data iex ses ve Seen Ppa eee EME Roe e A eae s 7 4 Instructions that Parse 2 2 ee 7 4 PULL Instruction a soes emane e na ai tee odile hi a D Ee 7 4 ARGEINSIUCHON 2 aair i Sern ator de ae aE Unk o eee R Uy s 7 4 PARSE VAR Instruction 0 000000 les 7 5 PARSE VALUE WITH Instruction 7 5 Ways of Parsing s 7 6 Bl nles 20d ou m tebe ot oa a case hh gem sudes Ma ele Gh wl at te Bo 7 6 SUING ond eh ed deeem ene Na ee a eant di 7 6 Varabl amp s l od uas a ie uude deu udo Res EE e 8 7 6 Number 7 ut ux xac e ede ep dox o Re Rr Pb uad 7 7 Parsing Multiple Strings as Arguments llli 7 9 Exercise Practice with Parsing ls 7 9 This chapter describes how to use compound variables and stems and shows various ways of parsing using templates Using Compound Variables and Stems Sometimes it is useful to store groups of related data in such a way that the data can be easily retrieved For example a list of employee names can be stored in an
147. ck sizes of subsequent data sets you might end in error To avoid error use the Preliminary Checklist and the other checklists provided and follow directions carefully REXX User s Guide 2 Execute SETUP by entering the following EXEC command READY EXEC rexx exec setup exec If the allocation was successful you should then see displayed on your screen Allocation to SYSEXEC completed To have SETUP execute when you log on and automatically allocate your data set to SYSEXEC type the same EXEC command in the COMMAND field of your LOGON panel TSO E LOGON PF1 PF13 gt Help PF3 PF15 gt Logoff PA1l gt Attention PA2 gt Reshow You may request specific HELP information by entering a in any entry field ENTER LOGON PARAMETERS BELOW RACF LOGON PARAMETERS USERID gt YOURID PASSWORD gt NEW PASSWORD gt PROCEDURE gt MYPROC GROUP IDENT gt ACCT NMBR gt 00123 SIZE gt 5800 PERFORI gt COMMAND gt EXEC rexx exec setup exec ENTER AN S BEFORE EACH OPTION DESIRED BELOW NOMAIL NONOTICE RECONNECT OIDCARD LL Appendix A Allocating Data Sets A 11 Checklist 4 Writing an Exec that Sets up Allocation to SYSPROC 1 Write an exec named SETUP that allocates data sets to SYSPROC Create a data set member named SETUP in your exec PDS In SETUP issue an ALLOCATE command that concatenat
148. command are placed in the buffer Below the buffer are elements placed on the stack before the MAKEBUF command t QUEUE MAKEBUF 4 Instructions that could be used to create the illustrated buffer are as follows MAKEBUF PUSH newX QUEUE newY Removing Elements from a Stack with a Buffer The buffer created by MAKEBUF does not prevent an exec from accessing elements below it After an exec removes the elements added after the MAKEBUF command then it removes elements added before the MAKEBUF command was issued Using the previous illustration when the exec issues three PULL instructions the following elements are removed from the data stack newX newY oldl To prevent a routine from accessing elements below the buffer you can use the QUEUED built in function as follows olditems QUEUED MAKEBUF PUSH QUEUE DO WHILE QUEUED gt olditems total items gt old number of items PULL END DROPBUF Dropping a Buffer with the DROPBUF Command When an exec has no more need for a buffer on the data stack it can use the TSO E REXX DROPBUF command to remove the buffer and its contents The DROPBUF command removes the most recently created buffer 11 10 05 390 V1R2 0 TSO E REXX User s Guide Creating a Buffer on the Data Stack DROPBUF A To drop a specific buffer on the data stack and all buffers created after it issue the DROPBUF command with the number of the buffer
149. confusion as to whether a residual stem variable value is meaningful you may want to clear the entire stem variable prior to entering the EXECIO command To clear all stem variables you can either Use the DROP instruction as follows which sets all stem variables to their uninitialized state DROP newvar Set all stem variables to nulls as follows newvar See EXECIO Example 6 under the heading Figure 12 7 on page 12 18 which shows the usage of the EXECIO command with stem variables SKIP To skip over a specified number of lines in a data set without placing them on the data stack or into variables EXECIO 24 DISKR myindd SKIP LIFO To read the information in LIFO order onto the stack In other words use the PUSH instruction to place the information on the stack FIFO To read the information in FIFO order onto the stack In other words use the QUEUE instruction to place the information on the stack If you do not specify either LIFO or FIFO FIFO is assumed Chapter 12 Processing Data and Input Output Processing 12 5 Using EXECIO to Process Information Writing Information to a Data Set To write information to a data set from the data stack or from a list of variables use EXECIO with the DISKW operand A typical EXECIO command to write all lines to the data set allocated to the ddname MYOUTDD might appear as EXECIO DISKW myoutdd FINIS The rest of this topic describes the types of inf
150. cords from the file BRR A RR REAR RR RIK RRR EA KKK ERK REIKI RIKKI k k k k k k RIA kkk kkk Since the outdd file is still closed at this point the x following EXECIO 0 DISKW command will open the file write 0 records and then close it This will effectively empty the data set allocated to outdd Any old records that were in this data set when this exec started will now be x deleted F k k k sede KR REA RRR RIK RRR ER KKK ERK EIR KK IKKE k k k k k k k KER IA k kk kkk EXECIO 0 DISKW outdd OPEN FINIS Empty the outdd file SAY File outdd is now empty END FREE FI indd FREE FI outdd EXIT Figure 12 6 EXECIO Example 5 continued Chapter 12 Processing Data and Input Output Processing 12 17 Using EXECIO to Process Information r EXECIO Example 6 RR RR RRR EER RRR ERR RR ER IKKE REXX RRR RRR RRR kkk k KERR RR RARER ERE kk This exec uses EXECIO to successively append the records from samplel data and then from sample2 data to the end of the data set all sample data It illustrates the effect of x residual data in STEM variables Data set samplel data x contains 20 records Data set sample2 data contains 10 x records x RR RR RRR RRR REE RRR ERIK KERIKERI RRA KER AK KEI k KK kk k k k k RAKE RR ERE kk ALLOC FI myindd1 DA samplel data SHR REUSE input file 1 ALLOC FI myindd2 DA sample2 data S
151. ction type the function name directly followed by one or more arguments within parentheses There can be no space between the function name and the left parenthesis function arguments Copyright IBM Corp 1988 1996 5 1 A function call can contain up to 20 arguments separated by commas Each argument can be one or more of the following e Blank function e Constant function 55 e Symbol function symbol name Literal string function With a literal string Option recognized by the function function option Another function function function arguments Combination of argument types function With a literal string 55 option When the function returns a value and all functions must return values the value replaces the function call In the following example the value returned is added to 7 and the sum is displayed SAY 7 function arguments A function call generally appears in an expression Therefore a function call like an expression does not usually appear in an instruction by itself 5 2 OS 390 V1R2 0 TSO E REXX User s Guide Example of a Function Calculations represented by functions often require many instructions For instance the simple calculation for finding the highest number in a group of three numbers might be written as follows r Finding a Maximum Number J etetekekekeeeekekeeesekekeeetekeeeieieek REXX RRR RRR RRR RK RRR RRR RRA RR ERE RE This exec receives three numbers
152. d ALTLIB ACTIVATE USER exec To display the active libraries in their current search order use the DISPLAY operand as follows ALTLIB DISPLAY For more information about the search order EXEC uses for execs and CLISTs see TSO E Command Reference SC28 1969 B 2 058 390 V1R2 0 TSO E REXX User s Guide Examples of the ALTLIB Command To deactivate searching for a certain level use the DEACTIVATE operand for example to deactivate searching for execs on the system level those allocated to SYSEXEC or SYSPROC issue ALTLIB DEACTIVATE SYSTEM exec And to reset exec searching back to the system level issue ALTLIB RESET Appendix B Specifying Alternate Libraries with the ALTLIB Command B 3 Examples of the ALTLIB Command B 4 08 390 V1R2 0 TSO E REXX User s Guide Appendix C Comparisons Between CLIST and REXX Accessing System Information llle C 2 Controlling Program Flow llle C 3 Deb gglng usu dnce PEGA GODS EAE RE EDR Aaa C 4 EX CUUION xu ass ue ada eh E UE eae ee DELS ASA RUE aw ae C 4 Interactive Communication llle C 5 Passing Information es C 5 Performing File VO 2 0020000022 eee ee C 6 Scr METER PR EE C 7 Using Functions les C 7 Usirig Variables Lowe BG eR Ee IE RS REN C 7 Both the CLIST language and the REXX language can be used in TSO E as procedures languages Some major features of REXX that are different from CLIST are
153. d data stack If no stack was previously created with the NEWSTACK command DELSTACK removes all the elements from the original stack Finding the Number of Stacks To find out how many stacks exist use the TSO E REXX QSTACK command QSTACK returns in the REXX special variable RC the total number of stacks including the original data stack NEWSTACK NEWSTACK QSTACK SAY The number of stacks is RC RC contains 3 11 16 05 390 V1R2 0 TSO E REXX User s Guide Protecting Elements in the Data Stack QSTACK returns the total number of stacks not just the ones created for a single exec Thus if an exec issued two NEWSTACK commands and called a routine that issued two more when the routine issues a QSTACK command RC returns the total number of stacks which is five For more information about these commands see TSO E REXX Reference SC28 1975 Additional Examples Data Stack Example 1 RRR R RRR EERE REE IKKE ERIK EERIE k k k k k REXX KR KKK KIRK REE REE EK ER k k kk kkk This exec tests several of the stack functions to see how they work together It uses the NEWSTACK and DELSTACK commands puts an element on the stack that exceeds 255 characters uses the LENGTH built in function to see how long the element is uses QUEUED built in function to see how many items are on the stack and then issues more PULL instructions than are elements on the stack x RR RR RRR ke dee
154. d e k k k kk ee k e kk e k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk element Attention please This is a test PUSH element NEWSTACK Create a new stack and protect elements previously placed on the stack longitem SAA is a definition a set of software interfaces conventions and protocols that provide a framework for designing and developing applications with cross system consistency The Systems Application Architecture defines a common programming interface you can use to develop applications and defines common communications support that you can use to connect those applications SAY The length of the element is LENGTH longitem characters The length of the element is 379 characters QUEUE longitem PULL anyitem SAY anyitem Displays the longitem quote in uppercase SAY There are QUEUED number of elements on the stack The QUEUED function returns 0 PULL emptyitem Pull an element from an empty stack Results in a blank screen and PULL waits for terminal x input To end the wait press ENTER x DELSTACK Remove the new stack and return to original stack PULL anyitem SAY anyitem Displays ATTENTION PLEASE THIS IS A TEST Chapter 11 Storing Information in the Data Stack 11 17 Protecting Elements in the Data Stack r Data Stack Example 2 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR RR KKK ER kkk kkk kkk
155. d output Trapping TSO E command output amp SYSOUTTRAP amp SYSOUTLINE OUTTRAP external function Error handling Error handling ERROR and ATTN statements SIGNAL ON ERROR SIGNAL ON FAILURE SIGNAL ON HALT SIGNAL ON NOVALUE and SIGNAL ON SYNTAX instructions CALL ON ERROR CALL ON FAILURE and CALL ON HALT instructions 1 1 For more information about REXX error handling instructions see TSO E REXX Reference SC28 1975 Execution CLIST REXX Explicit Explicit EXEC command EXEC MYNEW CLIST CLIST1 EXEC command EXEC MYNEW EXEC FIRST EXEC Implicit Implicit 1 Allocate concatenate to SYSPROC 2 Specify member name of PDS with or without C 4 08 390 V1R2 0 TSO E REXX User s Guide 1 Allocate concatenate to SYSPROC or SYSEXEC 2 Specify member name of PDS with or without Interactive Communication CLIST REXX Reading from the terminal Reading from the terminal READ READDVAL statements READ INPUTA INPUTB INPUTC PULL PARSE PULL PARSE UPPER PULL PARSE EXTERNAL instructions pull inputa inputb inputc Writing to the terminal Writing to the terminal WRITE statement WRITE Your previous entry was not valid SAY instruction say Your previous entry was not valid Passing Information CLIST REXX Receiving parameters in a CLIST Receiving arguments in an exec PROC statement PROC 1 DS
156. d to pass information to a function 6 12 used to pass information to a subroutine 6 4 valid name 3 2 value 3 3 within TSO E command 8 3 variable of a stem description 7 2 10 6 used with EXECIO function 12 5 12 7 used with OUTTRAP function 7 3 10 6 VLF data repository file compression 13 4 Communicating Your Comments to IBM OS 390 TSO E REXX User s Guide Publication No SC28 1974 00 If you especially like or dislike anything about this book please use one of the methods listed below to send your comments to IBM Whichever method you choose make sure you send your name address and telephone number if you would like a reply Feel free to comment on specific errors or omissions accuracy organization subject matter or completeness of this book However the comments you send should pertain to only the information in this manual and the way in which the information is presented To request additional publications or to ask questions or make comments about the functions of IBM products or systems you should talk to your IBM representative or to your IBM authorized remarketer When you send comments to IBM you grant IBM a nonexclusive right to use or distribute your comments in any way it believes appropriate without incurring any obligation to you If you are mailing a readers comment form RCF from a country other than the United States you can give the RCF to the local IBM branch office or IBM representative for postag
157. data set When you specify OPEN with EXECIO 0 it opens the data set and positions the file position pointer before the first record EXECIO 0 DISKR myindd OPEN Note If the data set is already open no operation is performed for OPEN FINIS To close the data set after reading it Closing the data set allows other execs to access it and its ddname It also resets the current positional pointer to the beginning of the data set STEM To read the information to either a list of compound variables that can be indexed or a list of variables appended with numbers Specifying STEM with a variable name ensures that a list of variables not the data stack receives the information EXECIO DISKR myindd STEM newvar In this example the list of compound variables has the stem newvar and lines of information or records from the data set are placed in variables newvar 1 newvar 2 newvar 3 and so forth The number of items in the list of compound variables is placed in the special variable newvar 0 Thus if 10 lines of information are read into the newvar variables newvar 0 contains the number 10 indicating that 10 records have been read Furthermore newvar 1 contains record 1 newvar 2 contains record 2 and so forth up to newvar 10 which contains record 10 All stem variables beyond newvar 10 for example variables newvar 11 and newvar 12 are residual and contain the value s held prior to entering the EXECIO command To avoid
158. data set name as an argument while implicitly invoking an exec enclose the data set name in a single set of quotation marks READY test2 userid rexx input Using Variables in Commands When a variable is used in a TSO E command the variable cannot be within quotation marks if its value is to be substituted Only variables outside quotation marks are processed by the language processor For example the variable name is assigned the data set name MYREXX EXEC When name is used in a LISTDS command it must remain outside the quotation marks placed around the command name myrexx exec LISTDS name STATUS When a variable represents a fully qualified data set name the name must be enclosed in two sets of quotation marks to ensure that one set of quotation marks remains as part of the value Chapter 8 Entering Commands from an Exec 8 3 Issuing TSO E Commands from an Exec name project rell new LISTDS name STATUS Another way to ensure that quotation marks appear around a fully qualified data set name when it appears as a variable is to include them as follows name project rell new LISTDS name STATUS Causing Interactive Commands to Prompt the User If your TSO E profile allows prompting when you issue an interactive command without operands you are prompted for operands For example when you issue the LISTDS command from READY you are prompted for a data set name READY listds ENTER DATA SET NAME
159. data set names Print or display VTOC information Reset statistics for members of ISPF library Initiate hardcopy output Display delete or print held job output Create change an application command table Convert old format menus messages to new format Format definition for formatted data Edit Browse Compare data sets Standard dialog Compare data sets Extended dialog Search data sets for strings of data Data Management Tools Appendix A Allocating Data Sets A 5 2 Specify a new data set name on the Data Set Utility panel and type A on the OPTION line On the next panel that appears type the name of the data set you want to allocate for example USERID REXX EXEC and enter A on the OPTION line OPTION gt a A Allocate new data set R Rename entire data set D Delete entire data set C Catalog data set U Uncatalog data set S Data set information short blank Data set information ISPF LIBRARY PROJECT gt userid GROUP gt rexx TYPE gt exec OTHER PARTITIONED SEQUENTIAL DATA SET DATA SET NAME gt OR VOLUME SERIAL gt left OIf not cataloged required for option C DATA SET PASSWORD gt If password protected 3 Specify the data set attributes on the Allocate New Data Set panel After you name the data set a panel appears on which you define the attributes of the data set Use the attributes recommended by your instal
160. data sets allocated to SYSPROC and you do not have a large number of REXX execs you may want to use SYSPROC only and not use SYSEXEC To use SYSPROC only a system programmer can change the search order on an installation wide basis or an individual can change the search order using the EXECUTIL SEARCHDD NO command You can issue the EXECUTIL SEARCHDD NO command directly from the terminal from an exec or CLIST and from the JCL input stream run in TSO E background The ALTLIB command can also affect search order For general information about ALTLIB see Appendix B Specifying Alternate Libraries with the ALTLIB Command on 13 4 05 390 V1R2 0 TSO E REXX User s Guide Running Execs in a TSO E Address Space page B 1 For more information about the EXECUTIL and ALTLIB commands see TSO E Command Reference SC28 1969 Running an Exec from a CLIST A CLIST can invoke an exec with the EXEC command explicitly or implicitly If it invokes an exec implicitly the exec must be in a PDS allocated to SYSEXEC or SYSPROC The CLIST that invokes the exec does not have to be allocated to SYSPROC After the invoked exec and other programs it might call complete control returns to the CLIST instruction following the invocation Similarly an exec can invoke a CLIST with the EXEC command explicitly or implicitly If it invokes a CLIST implicitly the CLIST must be in a PDS allocated to SYSPROG yet the exec does not have to be in a PDS allocated to a sys
161. dd FINIS FREE F updatedd Updating multiple lines To update multiple lines you can issue more than one EXECIO command to the same data set For example to update Mary Leone s user ID in addition to Amy Crandall s phone extension write the following instructions r Updating Multiple Specific Lines in a Data Set ALLOC DA dept5 employee list F updatedd OLD EXECIO 1 DISKRU updatedd 2 LIFO PULL line PUSH Crandall Amy AMY 5500 EXECIO 1 DISKW updatedd EXECIO 1 DISKRU updatedd 5 LIFO PULL line PUSH Leone Mary MARYL 5530 EXECIO 1 DISKW updatedd FINIS FREE F updatedd When you issue multiple EXECIO commands to the same data set before closing it and do not specify a line number the most current EXECIO command begins reading where the previous one left off Thus to scan a data set one line at a time and allow a user at a terminal to update each line you might write the following exec Chapter 12 Processing Data and Input Output Processing 12 11 Using EXECIO to Process Information r Example of Scanning Each Line for Update kkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX KK KK k ARR REAR k k Kk k K K k kk k k k kkk kk k This exec scans a data set whose name and size are specified by a user The user is given the option of changing each line as it appears If there is no change to the line the user presses Enter key to indicate that there is
162. de this information from the pseudonym files in your REXX execs For more information about host command environments and pseudonym files refer to TSO E REXX Reference SC28 1975 8 10 05 390 v1R2 0 TSO E REXX User s Guide Issuing Other Types of Commands from an Exec Changing the Host Command Environment You can change the host command environment either from the default or from whatever environment was previously established To change the host command environment use the ADDRESS instruction followed by the name of an environment The ADDRESS instruction has two forms one affects all commands issued after the instruction and one affects only a single command All commands When an ADDRESS instruction includes only the name of the host command environment all commands issued afterward within that exec are processed as that environment s commands ADDRESS ispexec Change the host command environment to ISPF edit DATASET dsname The ADDRESS instruction affects only the host command environment of the exec that uses the instruction When an exec calls an external routine the host command environment reverts back to the default environment regardless of the host command environment of the exec that called it Upon return to the original exec the host command environment that was previously established by an ADDRESS instruction is resumed Single command When an ADDRESS instruction includes both the name of the
163. does not match DATATYPE Returns a string indicating the input string is a particular data type such as a number or character SYMBOL Returns this state of the symbol variable literal or bad Conversion Functions Function Description B2X Returns a string in character format that represents the input binary string converted to hexadecimal Binary to hexadecimal C2D Returns the decimal value of the binary representation of the input string Character to Decimal C2X Returns a string in character format that represents the input string converted to hexadecimal Character to Hexadecimal D2C Returns a string in character format that represents the input decimal number converted to binary Decimal to Character D2X Returns a string in character format that represents the input decimal number converted to hexadecimal Decimal to Hexadecimal X2B Returns a string in character format that represents the input hexadecimal string converted to binary Hexadecimal to binary X2C Returns a string in character format that represents the input hexadecimal string converted to character Hexadecimal to Character X2D Returns the decimal representation of the input hexadecimal string Hexadecimal to Decimal Formatting Functions Function Description CENTER CENTRE Returns a string of a specified length with the i
164. ds of a TSO E command in a REXX exec you must place the subcommands onto the data stack before you issue the TSO E command 11 8 05 390 V1R2 0 TSO E REXX User s Guide Creating a Buffer on the Data Stack r Example of Passing Information from the Stack to a Command kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX k kkk kkk k kkk kk kkk kk kk kkk kk This exec prompts a user for a node and gets the user ID from a built in function It then calls an external subroutine to x check if the user s job is finished x The TRANSMIT command and its operands including a message with the status of the job are queued on the data stack to run after the exec terminates x RR RRR RRR ERE e e e kek k k e e AKER AIK KARRI KERIB KEK k KKK EIR kkk kkk k ERR SAY What is your node PULL node id USERID dest node id CALL jobcheck userid Go to a subroutine that checks job status IF RESULT done THEN note Your job is finished ELSE note Your job is not finished QUEUE transmit QUEUE dest line Specify that the message be in line mode QUEUE note QUEUE Insert a null to indicate line mode is over Creating a Buffer on the Data Stack When an exec calls a routine subroutine or function and both the exec and the routine use the data stack the stack becomes a way to share information However execs and routines that do not purposely share information from t
165. e EXEC command in TSO E Command Reference SC28 1969 You can type the EXEC command in the following places At the READY prompt READY EXEC rexx exec timegame exec From the COMMAND option of ISPF PDF eee ce Sorat hs shes ike TSO COMMAND PROCESSOR ENTER TSO COMMAND OR CLIST BELOW gt exec rexx exec timegame exec ENTER SESSION MANAGER MODE gt NO YES or NO e On the COMMAND line of any ISPF PDF panel as long as the EXEC command is preceded by the word tso PEPPER EDIT ENTRY PANEL COMMAND gt tso exec rexx exec timegame exec ISPF LIBRARY PROJECT gt PREFIX GROUP gt REXX gt gt gt TYPE gt EXEC EMBER gt TIMEGAME Blank for member selection list OTHER PARTITIONED OR SEQUENTIAL DATA SET DATA SET NAME gt VOLUME SERIAL gt If not cataloged DATA SET PASSWORD gt If password protected PROFILE NAME gt Blank defaults to data set type INITIAL MACRO gt LOCK gt YES YES NO or NEVER FORMAT NAME gt MIXED MODE gt NO YES or NO Chapter 2 Writing and Running a REXX Exec 2 11 Running an Exec Running an Exec Implicitly Running an exec implicitly means running an exec by simply entering the member name of the data set that contains the exec Before you can run an exec implicitly you must allocate the PDS that contains it to a system file SYSPROC or SYSEXEC
166. e NEWDATA kkkkkkkkkkkkkkkkkkkkkkkkkkkkx REXX setekeeeietekekekoekekejekdetekekekekedekekejekeeeieieex This external subroutine removes the data set name and the number of members from the stack and then issues the ALLOCATE command EK kk k k k e ek e e e k kek k k k e kk e ke k k kk k k k e k k e k k k kk k k k k kk k k k k kk k k k k kk k kk k kk k kk PULL name PULL number ALLOCATE DATASET name NEW SPACE 50 20 DIR number 6 DSORG PO RECFM V B LRECL 255 BLKSIZE 5100 RETURN RC The return code from the TSO E command sets the REXX special variable RC and is returned to the calling exec A 0 return code means no errors x Passing Information to Interactive Commands When your TSO E profile allows prompting most TSO E commands prompt you for missing operands For example the TRANSMIT command prompts you for a node and user ID when you do not include the destination with the command An exec can put responses to command prompts on the data stack Because of the information search order the data stack supplies the necessary information instead of a user at the terminal For example the following exec puts the TRANSMIT command and its operands on the data stack When the exec completes the TSO E data stack service continues to get input from the data stack Thus the TRANSMIT command is issued after the exec ends Issuing Subcommands of TSO E Commands To execute subcomman
167. e a blank string variable or number that represents column position Blank The simplest template is a group of variable names separated by blanks Each variable name gets one word of data in sequence except for the last which gets the remainder of the data The last variable name might then contain several words and possibly leading and trailing blanks PARSE VALUE Value with Blanks WITH pattern type pattern contains Value type contains with Blanks When there are more variables than data the extra variables are set to null PARSE VALUE Value with Extra Variables WITH datal data2 data3 data4 data5 datal contains Value x data2 contains with data3 contains Extra data4 contains Variables x data5 contains x A period in a template acts as a place holder The data that corresponds to the period is not assigned to a variable name You can use a period as a dummy variable within a group of variables or at the end of a template to collect unwanted information PARSE VALUE Value with Periods in it WITH pattern type pattern contains Value type contains Periods the periods replace the words with and in it String You can use a string in a template to separate data as long as the data includes the string as well The string becomes the point of separation and is not included as data phrase To be or not to be phrase containing comma
168. e and passes that information to an internal subroutine The subroutine then calculates the perimeter of the rectangle j BRREERRERIAAR ELAR EAERERA REA SARS ARSE ARAL ELAN LEA RE ERRER CEREAL AA ES AI PARSE ARG long wide CALL perimeter long wide SAY The perimeter is RESULT inches EXIT perimeter ARG length width perim 2 length 2 width RETURN ddl Notice the positional relationships between long and length and wide and width Also notice how information is received from variable perim in the special variable RESULT Using the ARG Built in Function Another way for a subroutine to receive arguments is with the ARG built in function This function returns the value of a particular argument specified by a number that represents the argument position For instance in the previous example instead of the ARG instruction ARG length width you can use the ARG function as follows length ARG 1 puts the first argument into length width ARG 2 puts the second argument into width More information about the ARG function appears in TSO E HEXX Reference SC28 1975 Chapter 6 Writing Subroutines and Functions 6 7 Writing a Subroutine Receiving Information from a Subroutine Although a subroutine can receive up to 20 arguments it can specify only one expression on the RETURN instruction That expression can be e A number RETURN 55 One or more variables whose values ar
169. e instruction in the example 2 6 OS 390 V1R2 0 TSO E REXX User s Guide Syntax of REXX Instructions pm EDIT USERID REXX EXEC TIMEGAME COLUMNS 009 080 COMMAND gt SCROLL gt HALF kkkkkk kkkkkkkkkkkkkkkkkkkkkkkk TOP OF DATA Axx KR eee ee eee ek ek eee ek dee ke ke ek dee dee ee 000001 33 x 90000 REXX k k kkk kkk kkk kkk kkk kkk 000002 This is an interactive REXX exec that asks a user for thex 000003 time and then displays the time from the TIME command 000004 xxx sce eee ee eee eee AKER AK RK eee A k k k kK k kK A kk k k k k kk kkk 000005 Gamel 000006 000007 SAY What time is it 000008 PULL usertime Put the user s response 000009 into a variable called 000010 usertime 000011 IF usertime THEN User didn t enter a time 000012 SAY 0 K Game s over 000013 ELSE 000014 DO 000015 SAY The computer says 000016 TSO system TIME command 000017 END 000018 000019 EXIT dekdekek kkkkkkkkkkkkkkkkkkkkkkkx BOTTOM OF DATA ee eee ek ee hee dee dee ke eee dee ee ee E J Keyword A keyword instruction tells the language processor to do something It begins with a REXX keyword that identifies what the language processor is to do For example SAY line 7 displays a string on the screen and PULL line 8 takes one or more words of input and puts them into the variable usertime IF THEN line 11 and ELSE line 13
170. e paid mailing f you prefer to send comments by mail use the RCF at the back of this book f you prefer to send comments by FAX use this number From Germany 07031 16 3456 Other countries 49 7031 16 3456 f you prefer to send comments electronically use this network ID IBM Mail Exchange DEIBMBM9 at IBMMAIL Internet e mail vsepubs vnet iobm com Make sure to include the following in your note e Title and publication number of this book Page number or topic to which your comment applies Readers Comments We d Like to Hear from You OS 390 TSO E REXX User s Guide Publication No SC28 1974 00 Overall how satisfied are you with the information in this book Very Very Satisfied Satisfied Neutral Dissatisfied Dissatisfied Overall satisfaction How satisfied are you that the information in this book is Ver Very Satisfied Satisfied Neutral Dissatisfied Dissatisfied Accurate Complete Easy to find Easy to understand Well organized Applicable to your tasks Please tell us how we can improve this book Thank you for your responses May we contact you Yes o No When you send comments to IBM you grant IBM a nonexclusi
171. e substituted or when no values were assigned return their names RETURN valuel value2 value3 A literal string RETURN Work complete e An arithmetic comparison or logical expression whose value is substituted RETURN 5 number Example Writing an Internal and an External Subroutine Write an exec that plays a simulated coin toss game of heads or tails between the computer and a user and displays the accumulated scores Start off with the message This is a game of chance Type heads tails or quit and press the Enter key This means that there are four possible inputs e HEADS TAILS QUIT None of these three not valid response Write an internal subroutine without arguments to check for valid input Send valid input to an external subroutine that compares the valid input with a random outcome Use the RANDOM built in function as RANDOM 0 1 and equate HEADS 0 TAILS 1 Return the result to the main program where results are tallied and displayed Good luck 6 8 05 390 V1R2 0 TSO E REXX User s Guide Writing a Subroutine ANSWER r Possible Solution Main Exec kk kkk kk kkk kkk k kkk kk kkk kkk kkk REX XK k k kk k k k kkk kk k k kk k k k k kk kkk k kkk kk This exec plays a simulated coin toss game between the computer and a user The user enters heads tails or quit The user is first checked for validity in an internal subroutine An ex
172. ed interchangeably according to availability and personal preference This book uses the backslash character The Strictly Equal and Equal Operators When two expressions are strictly equal everything including the blanks and case when the expressions are characters is exactly the same When two expressions are equal they are resolved to be the same The following expressions are all true WORD word returns 1 word word returns 1 word word returns 1 4e2 400 returns 1 4e2 100 returns 1 Using Comparison Expressions Often a comparison expression is used in IF THEN ELSE instructions The following example uses an IF THEN ELSE instruction to compare two values For more information about this instruction see IF THEN ELSE Instructions on page 4 2 3 8 05 390 V1R2 0 TSO E REXX User s Guide Using Expressions r Example Using A Comparison Expression kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX XK RRR RRR RRR KARR KERR RR RARER ERE kk This exec compares what you paid for lunch for two x days in a row and then comments on the comparison x RR RR RRR RRR REE RRR ERIK KERIKERI RIA KEK AK KKK k k k k kk A k k k kk kkk k kkk kk SAY What did you spend for lunch yesterday SAY Please do not include the dollar sign PARSE PULL last SAY What did you spend for lunch today SAY Please do not include the dollar sign PARSE PULL lunch IF lunch last THE
173. ed to press the Enter key again to resume tracing TRACE L Makes the language processor pause at labels only The instruction can also change the course of an exec such as by assigning a different value to a variable to force the execution of a particular branch in an IF THEN ELSE instruction In the following example RC is set by a previous command IF RC 0 THEN DO instructionl instruction2 END ELSE instructionA If during normal execution the command ends with other than a 0 return code the ELSE path will be taken To force taking the IF THEN path during interactive trace you can change the value of RC as follows during a pause RC 0 Re executing the Last Instruction Traced You can re execute the last instruction traced by entering an equal sign 2 with no blanks The language processor then re executes the previously traced instruction with values possibly modified by instructions if any were entered during the pause Chapter 9 Diagnosing Problems Within an Exec 9 7 Debugging Execs Ending Interactive Trace You can end interactive tracing in one of the following ways Use the TRACE OFF instruction Let the exec run until it ends Use the TRACE instruction ssue the EXECUTIL TE command TRACE OFF The TRACE OFF instruction ends tracing as stated in the message displayed at the beginning of interactive trace Interactive trace TRACE OFF to end debug ENTER to continue You can en
174. ed to shift either to the right with a or to the left Chapter 7 Manipulating Data 7 7 Parsing Data with a part starts at column 1 the preceding 1 is not coded but implied In the following example therefore the 5 part2 causes part2 to start in column 14526 the 5 part3 causes part3 to start in column 6 5 11 and so on quote Ignorance is bliss PARSE VAR quote partl 5 part2 5 part3 5 part4 part1 contains Ignor part2 contains ance part3 contains is bl part4 contains iss The use of the minus sign is similar to the use of the plus sign in that it is used to identify a relative position in the data string The minus sign is used to back up move to the left in the data string In the following example therefore the parti causes parti to start in column 1 implied the 10 part2 causes part2 to start in column 1 10 11 the 3 part3 causes part3 to start in column 11 3 14 and the 3 part4 causes part4 to start in column 14 3 11 quote Ignorance is bliss PARSE VAR quote part1 10 part2 3 part3 3 part4 partl contains Ignorance part2 contains is part3 contains bliss part4 contains is bliss e Variables You can define and use variables to provide further flexibility of a PARSE VAR instruction Define the variable prior to the parse instruction such as the movex variable in the following example With the PARSE instruction
175. ee Running an Exec Implicitly on page 2 12 and Appendix A Allocating Data Sets on page A 1 From another exec as an external function or subroutine as long as both execs are in the same PDS or the PDSs containing the execs are allocated to a system file for example SYSPROC or SYSEXEC For more information about Chapter 13 Using REXX in TSO E and Other MVS Address Spaces 13 3 Running Execs in a TSO E Address Space external functions and subroutines see Chapter 6 Writing Subroutines and Functions on page 6 1 From a CLIST or other program For more information see Running an Exec from a CLIST on page 13 5 Things to Consider When Allocating to a System File SYSPROC or SYSEXEC Allocating a partitioned data set containing execs to a system file allows you to e Run execs implicitly After a PDS is allocated to a system file you can run the exec by simply entering the member name which requires fewer keystrokes and is therefore faster to invoke e Invoke user written external functions and subroutines written in REXX that are in PDSs also allocated to SYSEXEC or SYSPROC Control search order You can concatenate the data sets within the file to control search order This is useful in testing a version of an exec placed earlier in the search order than the original version Compression In certain situations a REXX exec will be compressed to optimize usage of system storage These situations can ar
176. een Chapter 2 Writing and Running a REXX Exec 2 3 Syntax of REXX Instructions THIS IS A REXX STRING Note If any word in the statement is the name of a variable that has already been assigned a value REXX substitutes the value For information about variables see Using Variables on page 3 2 If a string contains an apostrophe you can enclose the literal string in double quotation marks SAY This isn t a CLIST instruction You can also use two single quotation marks in place of the apostrophe because a pair of single quotation marks is processed as one SAY This isn t a CLIST instruction Either way the outcome is the same This isn t a CLIST instruction The Format of REXX Instructions The REXX language uses a free format This means you can insert extra spaces between words and blank lines freely throughout the exec without causing an error A line usually contains one instruction except when it ends with a comma or contains a semicolon A comma is the continuation character and indicates that the instruction continues to the next line The comma when used in this manner also adds a space when the lines are concatenated A semicolon indicates the end of the instruction and is used to separate multiple instructions on one line Beginning an instruction An instruction can begin in any column on any line The following are all valid instructions SAY This is a literal string SAY This is a l
177. em level includes exec libraries previously allocated to file SYSEXEC or SYSPROC During implicit execution these libraries are searched after user or application libraries Using the ALTLIB Command The ALTLIB command offers several functions which you specify using the following operands ACTIVATE Allows implicit execution of execs in a library or libraries on the specified level s in the order specified DEACTIVATE Excludes the specified level from the search order DISPLAY Displays the current order in which exec libraries are searched for implicit execution RESET Resets searching to the system level only execs allocated to SYSEXEC or SYSPROC For complete information about the syntax of the ALTLIB command see TSO E Command Reference SC28 1969 Copyright IBM Corp 1988 1996 B 1 Examples of the ALTLIB Command Notes 1 With ALTLIB data sets concatenated to each of the levels can have differing characteristics logical record length and record format but the data sets within the same level must have the same characteristics 2 At the application and system levels ALTLIB uses the virtual lookaside facility VLF to provide potential increases in library search speed Stacking ALTLIB Requests On the application level you can stack up to eight activate requests with the top or current request active Application level libraries you define while running an ISPF application are in effect only while that ap
178. en read Stem variables newvar 1 newvar 2 through newvar 10 will contain the 10 records If we had not cleared the stem newvar with the previous DROP instruction variables newvar 11 through newvar 20 would still contain records 11 through 20 from the first data set However we would know that these values were not read by the last EXECIO DISKR since the current newvar 0 variable indicates that only 10 records were read by x that last EXECIO x k kk k k k e ek dee kde e ke k ee k k kk k eee k k k k k kk k k k k kk k k k k kk k k kk kk kkk Figure 12 8 EXECIO Example 6 continued Chapter 12 Processing Data and Input Output Processing 12 19 Using EXECIO to Process Information r EXECIO Example 6 continued SAY SAY SAY newvar 0 records have been read from sample2 data SAY DO i 1 TO newvar 0 Loop through all records x SAY newvar i Display the ith record x END EXECIO newvar 0 DISKW myoutdd STEM newvar Write exactly the number of records read IF rc 0 THEN If write was successful x DO SAY SAY newvar 0 records were written to all sample data END ELSE DO exec_RC RC Save exec return code SAY SAY Error during 2nd EXECIO DISKW return code is RC SAY END END ELSE DO exec_RC RC Save exec return code SAY SAY Error during 2nd EXECIO DISKR return code is RC SAY END END EXECIO 0 DISKW myo
179. endix A Allocating Data Sets on page A 1 Then try the example execs from the beginning of this chapter Run them explicitly with the EXEC command and see if the results you get are the same as the ones in this book If they are not why aren t they the same Now write an exec to allocate your PDS to SYSPROC or SYSEXEC using Checklist 3 on page A 10 or Checklist 4 on page A 12 Then run the example execs implicitly Which way is easier Interpreting Error Messages When you run an exec that contains an error an error message often displays the line on which the error occurred and gives an explanation of the error Error messages can result from syntax errors and from computational errors For example the following exec has a syntax error Chapter 2 Writing and Running a REXX Exec 2 13 Preventing Translation to Uppercase r Example of an Exec with a Syntax Error Ek kkk k k kkk ERR k kkk kkk kkk kkk REX K RRR RRR k k k RRA KR KER k k k RARER ERE RE This is an interactive REXX exec that asks the user for a name and then greets the user with the name supplied It contains a deliberate error EK kk k k k e ek e e e e kek k k k e kk e ke k k kk k k k ARK IK ERIK k kk k k k k kk k k k k kk kkk k kk k kk SAY Hello What s your name PULL who Get the person s name IF who THEN SAY Hello stranger ELSE SAY Hello who When the exec runs you see the following on your screen
180. eno 1 Count the record IF INDEX record JONES 0 THEN DO SAY Found in record lineno done yes SAY Record record END ELSE NOP END ELSE done yes END EXIT 0 Figure 12 1 EXECIO Example 1 Chapter 12 Processing Data and Input Output Processing 12 13 Using EXECIO to Process Information r EXECIO Example 2 RR RR RRR EERE REE kkk kkkkkkkkkkkx REXX RRR RRR RRR RRR kk k k k kkk kkk k kkk kk This exec copies records from data set my input to the end of data set my output Neither data set has been allocated to a ddname It assumes that the input data set has no null lines RR RR RRR RRR RE deje dee e kk de ke k k kk k k k k kk e k k k kk k k k k kk k k k k kk k k k k kk k kk k kkk kk ALLOC DA my input F indd SHR REUSE ALLOC DA my output F outdd MOD REUSE SAY Copying EXECIO DISKR indd FINIS QUEUE Insert a null line at the end to indicate end of file EXECIO DISKW outdd FINIS SAY Copy complete FREE F indd outdd EXIT 0 Figure 12 2 EXECIO Example 2 EXECIO Example 3 kkkkkkkkkkkkkkkkkkkkkkkkkkkxk REX XK RRR RRR RRR KERR RRR RRR RRA RRR k kkk kk This exec reads five records from the data set allocated to x MYINDD starting with the third record It strips trailing blanks from the records and then writes any record that is longer than 20 characters The file is not closed when the e
181. ent SETLANG returns a 3 character code that indicates the language in which REXX messages are currently being displayed Figure 10 1 shows the language codes that replace the function call and the corresponding language for each code You can optionally specify one of the language codes on the function call to change the language in which REXX messages are displayed In this case SETLANG sets the language to the code specified and returns the language code of the previous language setting The language codes you can specify on SETLANG depend on the language features that are installed on your system Figure 10 1 Page 1 of 2 Language Codes for SETLANG Function That Replace the Function Call Language Language Code CHS Simplified Chinese CHT Traditional Chinese DAN Danish DEU German ENP US English all uppercase ENU US English mixed case uppercase and lowercase Chapter 10 Using TSO E External Functions 10 7 TSO E External Functions Figure 10 1 Page 2 of 2 Language Codes for SETLANG Function That Replace the Function Call Language Language Code ESP Spanish FRA French JPN Japanese KOR Korean PTB Brazilian Portuguese To find out the language in which REXX messages are currently being displayed issue the SETLANG function followed by empty parentheses curlang SETLANG curlang is set to the 3 character code of the current language setting
182. eous Functions ens 5 7 Testing Input with Built In Functions aoaaa aaae 5 8 Exercise Writing an Exec with Built In Functions 5 8 This chapter defines what a function is and describes how to use the built in functions What is a Function A function is a sequence of instructions that can receive data process that data and return a value In REXX there are several kinds of functions Built in functions These functions are built into the language processor More about built in functions appears later in this chapter e User written functions These functions are written by an individual user or supplied by an installation and can be internal or external An internal function is part of the current exec that starts at a label An external function is a self contained program or exec outside of the calling exec More information about user written functions appears in Writing a Function on page 6 11 Function packages These are groups of functions and subroutines written by an individual user or supplied by an installation They are link edited into load modules and categorized as user local and system TSO E external functions are provided in a system function package More information about TSO E external functions appears in TSO E External Functions on page 10 1 Regardless of the kind of function all functions return a value to the exec that issued the function call To call a fun
183. erface Information Trademarks This book is intended to help customers to learn how to write REXX execs It contains information about OS 390 TSO E REXX This book documents General use Programming Interfaces and Associated Guidance Information provided by TSO E General use programming interfaces allow the customer to write programs and obtain the services of TSO E The following terms are trademarks of the IBM Corporation in the United States or other countries or both e CICS e DFSMS MVS e IBM e IMS e MVS DFP e MVS ESA Operating System 2 Operating System 400 OS 2 OS 390 OS 400 e RACF SAA e Systems Application Architecture Other company product and service names which may be denoted by a double asterisk may be trademarks or service marks of others Xil OS 390 V1R2 0 TSO E REXX User s Guide About This Book This book describes how to use the TSO E Procedures Language MVS REXX processor called the language processor and the REstructured eXtended eXecutor REXX language Together the language processor and the REXX language are known as TSO E REXX TSO E REXX is the implementation of the Systems Application Architecture SAA Procedures Language on the MVS system Who Should Use This Book This book is intended for anyone who wants to learn how to write REXX programs More specifically the audience is programmers who may range from the inexperienced to those with extensive programmin
184. es RC and SIGL to help diagnose problems within execs RC RC stands for return code and is set every time a command is issued When a command ends without error RC is usually set to 0 When a command ends in error RC is set to whatever return code is assigned to that error For example the previous incorrect LISTDS command is issued followed by the RC special variable in a SAY instruction LISTDS SAY The return code from the command is RC This results in the following MISSING DATA SET NAME INVALID KEYWORD The return code from the command is 12 KKK The RC variable can be especially useful in an IF instruction to determine which path an exec should take ALLOC DA dsname F SYSPROC SHR REUSE IF RC 0 THEN CALL errorl ELSE NOP Note The value of RC is set by every command and might not remain the same for the duration of an exec When using RC make sure it contains the return code of the command you want to test SIGL The SIGL special variable is used in connection with a transfer of control within an exec because of a function or a SIGNAL or CALL instruction When the language processor transfers control to another routine or another part of the exec it sets the SIGL special variable to the line number from which the transfer occurred 000001 REXX 000005 CALL routine 000008 000009 routine 000010 SAY We came here from line SIGL SIGL is set to 3 000011 RETURN If the called rout
185. es continues as long as there is output Output from the most recent command is placed after the previous command s output The total number of lines trapped is stored in varo x OUTTRAP var LISTC SAY The number of lines trapped is var0 To limit the number of lines of output saved you can specify a limit for example 5 after the variable name x OUTTRAP var 5 This results in up to 5 lines of command output stored in var1 var2 var3 var4 var5 and var0 contains the number 5 Subsequent lines of command output are not saved The following example traps output from two commands and then displays the member names from a partitioned data set named MYNEW EXEC The stem variable includes a period which causes the lines of output to be stored in a series of compound variables For more information about compound variables see Using Compound Variables and Stems on page 7 1 x OUTTRAP var LISTC SAY The number of lines trapped is var 0 could display 205 lines var Q 1 LISTDS mynew exec MEMBERS SAY The number of lines trapped is var 0 could display 210 DO i lines TO var 0 SAY var i displays 5 members END To turn trapping off reissue the OUTTRAP function with the word OFF x OUTTRAP OFF turns trapping OFF The OUTTRAP function can be used only in REXX execs that run in the TSO E address space The OUTTRAP function does not trap all lines of command output from all TS
186. es your PDS to the beginning of all the data sets already allocated to SYSPROC Include the data sets allocated to SYSPROC from the list in the Preliminary Checklist on page A 3 If there are no other data sets allocated to SYSPROC specify your PDS only Your SETUP exec could look like the following example ELSE r Sample SETUP Exec J oetetekekekeeeekekeeesekekeeetekeeeieiexcek REX KX RR RRR RK RRR KEKE IRR RRA RR RR ERE RR This exec is an example of how to allocate a private PDS named USERID REXX EXEC to the beginning of a concatenation to SYSPROC that consists of 3 other data sets named ICQ INFOCNTR ICQCLIB SYS1 TSO CLIST and ISP ISPF CLISTS After the ALLOCATE x command executes a message indicates whether the command was successful or not x RR kk RRR RR RRR ERR KR ERIK KERIKERI KERIKERI KKK IK KKK IK k k k kk kkk k kkk kk ALLOC FILE SYSPROC DATASET rexx exec icq infocntr icqclib sysl tso clist isp ispf clists SHR REUSE IF RC 0 THEN SAY Allocation to SYSPROC completed SAY Allocation to SYSPROC failed Note The order in which you list data sets in an ALLOCATE command is the order in which they are concatenated and searched To give your execs priority in the search order list your data set of execs before other data sets Generally all the data sets in the list should have the same record format either RECFM VB or RECFM F
187. etion of requested operation 1 Data was truncated during DISKW operation Chapter 12 Processing Data and Input Output Processing 12 7 Using EXECIO to Process Information Return Code Meaning 2 End of file reached before the specified number of lines were read during a DISKR or DISKRU operation This return code does not occur when is specified for number of lines because the remainder of the file is always read 4 An empty data set was found within a concatenation of data sets during a DISKR or DISKRU operation The file was not successfully opened and no data was returned 20 Severe error EXECIO completed unsuccessfully and a message is issued When to Use the EXECIO Command The various operands and combination of operands of the EXECIO command permit you to do many types of I O For example you can use the EXECIO command to Copy information from one data set to another Copy an entire data set Copy parts of a data set Add information to the end of a sequential data set Copy information to and from a list of compound variables Update information in a data set Copying Information From One Data Set to Another Before you can copy one data set to another the data sets must be either sequential data sets or members of a PDS and they must be pre allocated Following are examples of ways to allocate and copy data sets using the EXECIO command Copying an
188. exec in TSO E can issue TSO E commands APPC MVS calls MVS module invocations ISPF commands and ISPF PDF EDIT commands If you have TSO E CONSOLE command authority and an extended MCS console session is active you can also issue MVS system and subsystem commands in a REXX exec Each type of invocation is associated with a different host command environment What is a Host Command Environment An environment for executing commands is called a host command environment Before an exec runs an active host command environment is defined to handle commands issued by the exec When the language processor encounters a command it passes the command to the host command environment for processing When a REXX exec runs on a host system there is at least one default environment available for executing commands The default host command environments available in TSO E REXX are as follows TSO the environment in which TSO E commands and TSO E REXX commands execute in the TSO E address space MVS the environment in which TSO E REXX commands execute in a non TSO E address space LINK an environment that links to modules on the same task level LINKMVS an environment that links to modules on the same task level This environment allows you to pass multiple parameters to an invoked module and allows the invoked module to update the parameters The parameters you pass to the module include a length identifier LINKPGM an environment th
189. exec with i 6 Example of a Problem Caused by Passing Information in a Variable kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX KX FR k k RRR kkk k KER kk kkk k kkk ERE kk This exec uses an instruction in a DO loop to call an internal function A problem occurs because the function also uses a DO loop with the same control variable as the main exec The DO loop in the main exec repeats only once x RR RR RRR kde deje RAK KERIKERI KEK k kk k k k KEI k KKK IKK k kk KKK EKER numberl 5 number2 10 DO i 1 T05 SAY add Displays 105 END EXIT add DO i 1 T05 answer number1 number2 numberl1 number2 number2 answer END RETURN answer To avoid this kind of problem in an internal function you can use e The PROCEDURE instruction as described in the next topic Different variable names in a function Protecting Variables with the PROCEDURE Instruction When you use the PROCEDURE instruction immediately following the function label all variables used in the function become local to the function and are shielded from the main part of Chapter 6 Writing Subroutines and Functions 6 13 Writing a Function the exec You can also use the PROCEDURE EXPOSE instruction to protect all but a few specified variables The following two examples show the differing results when a function uses the PROCEDURE instruction and when it doesn t Example Using the PROCEDURE
190. expression 5 5 is evaluated as 10 answer 5 5 answer gets the value 10 If the arithmetic expression is in quotation marks the expression is evaluated as a string answer 5 5 answer gets the value 5 5 To both evaluate and execute an expression you can use the INTERPRET instruction Using the INTERPRET Instruction The INTERPRET instruction not only evaluates an expression but also treats it as an instruction after it is evaluated Thus if a combination of the previous examples were used with the INTERPRET instruction answer becomes 10 answer 5 5 INTERPRET say answer 5 5 displays 10 5 5 x You can also group a number of instructions within a string assign the string to a variable and use the INTERPRET instruction to execute the instructions assigned to the variable action DO 3 SAY Hello END INTERPRET action results in Hello Hello Hello Because the INTERPRET instruction causes dynamic modification use it very carefully For more information about the INTERPRET instruction see TSO E REXX Reference SC28 1975 Using EXECIO to Process Information to and from Data Sets An exec uses the EXECIO command to perform the input and output I O of information to and from a data set The information can be stored in the data stack for serialized processing or in a list of variables for random processing When to Use the EXECIO Command The various ope
191. f instructions that can receive data process that data and return a value The routines can be Internal The routine is within the current exec marked by a label and used only by that exec External A program or exec in a member of a partitioned data set that can be called by one or more execs In order for an exec to call the routine the exec and the routine must be allocated to a system file for example SYSEXEC or SYSPROC or be in the same PDS For more information about allocating to a system file see Appendix A Allocating Data Sets on page A 1 In many aspects subroutines and functions are the same yet they are different in a few major aspects such as the way they are called and the way they return values Calling a subroutine To call a subroutine use the CALL instruction followed by the subroutine name label or exec member name and optionally followed by up to 20 arguments separated by commas The subroutine call is an entire instruction CALL subroutine name argumentl argument2 Copyright IBM Corp 1988 1996 6 1 When to Write Subroutines vs Functions Calling a function To call a function use the function name label or exec member name immediately followed by parentheses that can contain arguments There can be no space between the function name and the parentheses The function call is part of an instruction for example an assignment instruction x function argumentl argument2 e Ret
192. following example what is the outcome Chapter 4 Controlling the Flow Within an Exec 4 3 Using Conditional Instructions r Example of Missing Instructions RR RR RRR RE de REE kk KR ERIK REE RARER REXX KKK KKK AKER AREER AK kk RARER This exec demonstrates what can happen when you do not include DOs ENDs and ELSEs in nested IF THEN ELSE instructions RR kk RR RR ek e REE R RR E RIK KERIKERI KRABI KK REI KKK II KKK RAK k kkk kk weather fine tenniscourt occupied IF weather fine THEN SAY What a lovely day IF tenniscourt free THEN SAY Shall we play tennis ELSE SAY Shall we take our raincoats By looking at the exec you might assume the ELSE belongs to the first IF However the language processor associates an ELSE with the nearest unpaired IF The outcome is as follows What a lovely day Shall we take our raincoats 4 4 08 390 V1R2 0 TSO E REXX User s Guide Using Conditional Instructions Exercise Using the IF THEN ELSE Instruction Write the REXX instructions for the following flowchart IF False True lt IF i False True Fal 3 alse True y IF False True lt gt B 1 e pes A 1 ANSWER Possible Solution IF A 0 THEN IF C 2 THEN B 1 ELSE NOP ELSE IF B IF 2 THEN 3 THEN I Do0 ill ELSE A 3 ELSE NOP Chapter 4 Controlling the Flow Within an Exec 4 5
193. formation about the data stack see Chapter 11 Storing Information in the Data Stack on page 11 1 8 4 08 390 V1R2 0 TSO E REXX User s Guide Issuing TSO E Commands from an Exec Invoking Another Exec as a Command Previously this book discussed how to invoke another exec as an external routine Chapter 6 Writing Subroutines and Functions on page 6 1 You can also invoke an exec from another exec explicitly with the EXEC command or implicitly by member name Like an external routine an exec invoked explicitly or implicitly can return a value to the caller with the RETURN or EXIT instruction Unlike an external routine which passes a value to the special variable RESULT the invoked exec passes a value to the REXX special variable RC Invoking Another Exec with the EXEC Command To explicitly invoke another exec from within an exec issue the EXEC command as you would any other TSO E command The called exec should end with a RETURN or EXIT instruction ensuring that control returns to the caller The REXX special variable RC is set to the return code from the EXEC command You can optionally return a value to the caller on the RETURN or EXIT instruction When control passes back to the caller the REXX special variable RC is set to the value of the expression returned on the RETURN or EXIT instruction For example to invoke an exec named MYREXX EXEC CALC and pass it an argument of four numbers you could include the following
194. formation in the Data Stack What is a Data Stack lol 11 1 Manipulating the Data Stack 0 0 00 00000000000 11 2 Adding Elements to the Data Stack 11 2 Removing Elements from the Stack 11 3 Determining the Number of Elements on the Stack 11 3 Exercise Using the Data Stack 11 3 Processing of the Data Stack ol lllo lll 11 5 Using the Data Stack lll llle 11 6 Passing Information Between a Routine and the Main Exec 11 6 Passing Information to Interactive Commands 11 8 Issuing Subcommands of TSO E Commands 11 8 Creating a Buffer on the Data Stack 2 0 11 9 Creating a Buffer with the MAKEBUF Command 11 10 Removing Elements from a Stack with a Buffer 11 10 Dropping a Buffer with the DROPBUF Command 11 10 Finding the Number of Buffers with the QBUF Command 11 11 Finding the Number of Elements In a Buffer lin 11 11 Exercises Creating a Buffer on the Data Stack 11 12 Protecting Elements in the Data Stack 11 14 Creating a New Data Stack with the NEWSTACK Command 11 15 Deleting a Private Stack with the DELSTACK Command 11 16 Finding the Number of Stacks 222005 11 16 Additional Examples s 11 17 This chapter describes how to use t
195. from a user and analyzes which number is the greatest x RR kk RRR RARER RE deed e k k k kk k k eee k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk PARSE ARG number1 number2 number3 IF numberl gt number2 THEN IF numberl gt number3 THEN greatest numberl ELSE greatest number3 ELSE IF number2 gt number3 THEN greatest number2 ELSE greatest number3 RETURN greatest Rather than writing multiple instructions every time you want to find the maximum of a group of three numbers you can use a built in function that does the calculation for you and returns the maximum number The function is called MAX and is used as follows MAX number1 number2 number3 To find the maximum of 45 2 number 199 and put the maximum into the symbol biggest write the following instruction biggest MAX 45 2 number 199 Chapter 5 Using Functions 5 3 Built In Functions Built In Functions Over 50 functions are built into the language processor The built in functions fall into the following categories Arithmetic functions These functions evaluate numbers from the argument and return a particular value Comparison functions These functions compare numbers and or strings and return a value Conversion functions These functions convert one type of data representation to another type of data representation Formatting functions These functions manipulate the characters and spacin
196. g Variables SO and SI cannot be contiguous Nesting of SO SI is not permitted A DBCS name cannot contain a DBCS blank X 4040 e The variable name should not be RC SIGL or RESULT which are REXX special variables More about special variables appears later in this book Examples of acceptable variable names are ANSWER 98B X Word3 number the ultimate value Also if ETMODE is set on the following are valid DBCS variable names where represents shift out and gt represents shift in X Y and Z represent DBCS characters and lowercase letters and numbers represent themselves X Y Z number X Y Z X Y21234 Z Variable Values The value of the variable which is the value the variable name represents might be categorized as follows e A constant which is a number that is expressed as An integer 12 A decimal 12 5 A floating point number 1 25E2 A signed number 12 A string constant 12 A string which is one or more words that may or may not be enclosed in quotation marks such as This value is a string This value is a literal string The value from another variable such as variablel variable2 In the above example variablel changes to the value of variable2 but variable2 remains the same An expression which is something that needs to be calculated such as variable2 12 12 6 variable2 becomes 23 4 Before a variable is assig
197. g data into one or more variable names An exec can parse an argument to break it up into smaller parts or parse a string to assign each word to a variable name Parsing is also useful to format data into columns Instructions that Parse There are several REXX instructions and variations of instructions that parse data PULL Instruction n earlier chapters PULL was described as an instruction that reads input from the terminal and assigns it to one or more variables If however the data stack contains information the PULL instruction takes information from the data stack and when the data stack is empty PULL takes information from the terminal For information about the data stack see Chapter 11 Storing Information in the Data Stack on page 11 1 PULL changes character information to uppercase and assigns it to one or more variable names When PULL is followed by more than one variable it parses the information into the available variables SAY What is the quote for the day user enters Knowledge is power PULL wordl word2 word3 wordl contains KNOWLEDGE word2 contains IS word3 contains POWER The PARSE PULL instruction assigns information without altering it to variable names SAY What is the quote for the day user enters Knowledge is power PARSE PULL wordl word2 word3 wordl contains Knowledge word2 contains is word3 contains power PARSE UPPE
198. g experience particularly in writing CLISTs for TSO E Because of the broad range of experience in readers this book is divided into two parts Part 1 PART Learning the REXX Language is for inexperienced programmers who are somewhat familiar with TSO E commands and have used the Interactive System Productivity Facility Program Development Facility ISPF PDF in TSO E Programmers unfamiliar with TSO E should first read the OS 390 TSO E Primer GC28 1967 Experienced programmers new to REXX can also read this section to learn the basics of the REXX language e Part 2 PART Il Using REXX is for programmers already familiar with the REXX language and experienced with the workings of TSO E It describes more complex aspects of the REXX language and how they work in TSO E as well as in other MVS address spaces If you are a new programmer you might want to concentrate on the first part If you are an experienced TSO E programmer you might want to read the first part and concentrate on the second part How This Book Is Organized In addition to the two parts described in the preceding paragraphs there are three appendixes at the end of the book Appendix A Allocating Data Sets contains checklists for the tasks of creating and editing a data set and for allocating a data set to a system file Appendix B Specifying Alternate Libraries with the ALTLIB Command describes using the ALTLIB command e Appendix C
199. g in strings supplied in the argument String manipulating functions These functions analyze a string supplied in the argument or a variable representing a string and return a particular value Miscellaneous functions These functions do not clearly fit into any of the other categories The following tables briefly describe the functions in each category For a complete description of these functions see TSO E REXX Reference SC28 1975 Arithmetic Functions Function Description ABS Returns the absolute value of the input number DIGITS Returns the current setting of NUMERIC DIGITS FORM Returns the current setting of NUMERIC FORM FUZZ Returns the current setting of NUMERIC FUZZ MAX Returns the largest number from the list specified formatted according to the current NUMERIC settings MIN Returns the smallest number from the list specified formatted according to the current NUMERIC settings RANDOM Returns a quasi random non negative whole number in the range specified SIGN Returns a number that indicates the sign of the input number TRUNC Returns the integer part of the input number and optionally a specified number of decimal places 5 4 OS 390 V1R2 0 TSO E REXX User s Guide Comparison Functions Built In Functions Function Description COMPARE Returns 0 if the two input strings are identical Otherwise returns the position of the first character that
200. he REXX data stack to store information Also this chapter describes how to add a buffer to a data stack and how to create a private data stack in TSO E What is a Data Stack REXX in TSO E uses an expandable data structure called a data stack to store information The data stack combines characteristics of a conventional stack and queue Stacks and queues are similar types of data structures used to temporarily hold data items elements until needed When elements are needed they are removed from the top of the data structure The basic difference between a stack and a queue is where elements are added as shown in the following figure Elements are added to the top of a stack and to the bottom of a queue Using a stack the last element added to the stack elem6 is the first removed Because elements are placed on the top of a stack and removed from the top the newest elements on a stack are the ones processed first The technique is called LIFO last in first out Using a queue the first element added to the queue elem1 is the first removed Because elements are placed on the bottom of a queue and removed from the top the oldest elements on a queue are the ones processed first The technique is called FIFO first in first out Copyright IBM Corp 1988 1996 11 1 Manipulating the Data Stack Stack Queue 4 As shown in the following figure the data stack that REXX uses combines the techniques used in adding ele
201. he data stack might unintentionally do so and end in error To help prevent this TSO E provides the MAKEBUF command that creates a buffer which you can think of as an extension to the stack and the DROPBUF command that deletes the buffer and all elements within it Although the buffer does not prevent the PULL instruction from accessing elements placed on the stack before the buffer was created it is a way for an exec to create a temporary extension to the stack The buffer allows an exec to 1 Use the QUEUE instruction to insert elements in FIFO order on a stack that already contains elements 2 Have temporary storage that it can delete easily with the DROPBUF command An exec can create multiple buffers before dropping them Every time MAKEBUF creates a new buffer the REXX special variable RC is set with the number of the buffer created Thus if an exec issues three MAKEBUF commands RC is set to 3 after the third MAKEBUF command Note To protect elements on the stack an exec can create a new stack with the NEWSTACK command For information about the NEWSTACK command see Protecting Elements in the Data Stack on page 11 14 Chapter 11 Storing Information in the Data Stack 11 9 Creating a Buffer on the Data Stack Creating a Buffer with the MAKEBUF Command To create a buffer on the data stack before adding more elements to the stack use the TSO E REXX MAKEBUF command All elements added to the data stack after the MAKEBUF
202. iables 12 5 12 7 using the EXECIO command 12 2 12 3 writing from compound variables 12 7 writing to a data set 12 6 instruction adding during interactive trace 9 7 ADDRESS 8 11 ARG 2 17 6 6 6 15 7 4 blank 2 8 CALL RETURN 4 21 comment 2 8 conditional 4 1 continuing to the next line 2 4 DO FOREVER 4 11 DO UNTIL 4 16 DO WHILE 4 14 DO END 4 8 entering 2 3 EXIT 4 20 6 3 6 11 9 8 formatting 2 4 IF THEN ELSE 4 2 INTERPRET 12 2 interrupt 4 1 ITERATE 4 12 LEAVE 4 12 4 18 literal string 2 3 looping 4 1 PARSE 2 15 2 18 PARSE ARG 7 5 PARSE EXTERNAL 11 5 PARSE PULL 7 4 11 3 PARSE UPPER ARG 7 5 PARSE UPPER PULL 7 4 PARSE UPPER VALUE 7 5 PARSE UPPER VAR 7 5 PARSE VALUE WITH 7 5 PARSE VAR 7 5 PROCEDURE 6 5 6 13 PROCEDURE EXPOSE 6 6 6 14 PULL 2 16 7 4 11 3 PUSH 11 2 QUEUE 11 2 re executing during interactive trace 9 7 SAY 2 2 SELECT WHEN OTHERWISE END 4 6 SIGNAL 4 22 Index X 5 instruction continued SIGNAL ON ERROR 9 3 syntax 2 3 TRACE ending tracing 9 8 interactive tracing 9 4 tracing command 9 2 tracing expression 3 14 type of assignment 2 7 command 2 8 keyword 2 7 label 2 8 null 2 8 using blank 2 4 using comma 2 4 using quotation mark 2 3 8 2 using semicolon 2 5 writing 2 3 interactive debug facility adding an instruction 9 7 continuing 9 7 description 9 4 ending 9 7 9 8 option 9 7 re executing the last instruction traced 9 7 starting 9 4 interactive trace See interactive debug facility inte
203. igns the first number 42 to number1 and the second number 21 to number2 If the number of values is fewer or more than the number of variable names after the PULL or the ARG instruction errors can occur as described in the following sections Specifying Too Few Values When you specify fewer values than the number of variables following the PULL or ARG instruction the extra variables are set to null For example you pass only one number to add EXEC rexx exec add 42 exec The first variable following the ARG instruction number1 is assigned the value 42 The second variable number2 is set to null In this situation the exec ends with an error when it tries to add the two variables In other situations the exec might not end in error Specifying Too Many Values When you specify more values than the number of variables following the PULL or ARG instruction the last variable gets the remaining values For example you pass three numbers to add EXEC rexx exec add 42 21 10 exec Chapter 2 Writing and Running a REXX Exec 2 17 Passing Information to an Exec The first variable following the ARG instruction number1 is assigned the value 42 The second variable gets both 21 10 In this situation the exec ends with an error when it tries to add the two variables In other situations the exec might not end in error To prevent the last variable from getting the remaining values use a period at the end of the
204. ine itself calls another routine SIGL is reset to the line number from which the most recent transfer occurred SIGL and the SIGNAL ON ERROR instruction can help determine what command caused an error and what the error was When SIGNAL ON ERROR is included in Chapter 9 Diagnosing Problems Within an Exec 9 3 Debugging Execs an exec any host command that returns a nonzero return code causes a transfer of control to a routine named error The error routine runs regardless of other actions that would normally take place such as the display of error messages 000001 REXX x 000002 SIGNAL ON ERROR 000003 ALLOC DA new data LIKE old data 000008 LISTDS 000011 EXIT 000012 000013 ERROR 000014 SAY The return code from the command on line SIGL is RC 000015 Displays 000016 The return code from the command on line 5 is 12 For more information about the SIGNAL instruction see TSO E REXX Reference SC28 1975 Tracing with the Interactive Debug Facility The interactive debug facility permits a user to interactively control the execution of an exec A user can view the tracing of various types of instructions separated by pauses as the exec runs During a pause a user can continue to the next traced instruction insert instructions re execute the previous instruction and change or terminate interactive tracing Starting Interactive Tracing You can start interactive tracing with either the option of the TR
205. ing The first argument is a season and the other two can be yes or no x RR RAR RRR ER RRR e kek k k k e kk e ke k k kk k k k k kk e k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk PARSE ARG season snowing broken_leg IF season winter snowing yes amp broken_leg no THEN SAY Go skiing ELSE SAY Stay home When arguments passed to this example are spring yes no the IF clause translates as follows IF season winter snowing yes amp broken leg no THEN false true true true true As a result when you run the exec you see the message Go skiing Exercises Using Logical Expressions A student applying to colleges has decided to pick ones according to the following specifications IF inexpensive scholarship amp reputable nearby THEN SAY I ll consider it ELSE SAY Forget it A college is inexpensive did not offer a scholarship is reputable but is over 1000 miles away Should the student apply ANSWER Yes The conditional instruction works out as follows IF inexpensive scholarship amp reputable nearby THEN true false true false true true true Chapter 3 Using Variables and Expressions 3 11 Using Expressions Concatenation Operators Concatenation operators combine two terms into one The terms can be strings variables expressions or constants Co
206. ion call However all functions both internal and external must return a value Passing Information by Using Variables When an exec and its internal function share the same variables the value of a variable is what was last assigned regardless of whether the assignment was in the main part of the exec or in the function In the following example the value of answer is assigned in the function and displayed in the main part of the exec The variables number1 number2 and answer are shared In addition the value of answer replaces the function call because answer follows the RETURN instruction 6 12 0S 390 V1R2 0 TSO E REXX User s Guide Writing a Function r Example of Passing Information in a Variable kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX KX RRR RR RRR KIRK KER kk kkk RR RR ER ERE This exec receives a calculated value from an internal function and displays that value x RR kk RRR RRR REE R KR e e kk KERRI RIA KERIKERI KK REA KKK RIKKI KKK EERE RE numberl 5 number2 10 SAY add Displays 15 SAY answer Also displays 15 EXIT add answer numberl number2 RETURN answer Using the same variables in an exec and its internal function can sometimes create problems In the following example the main part of the exec and the function use the same control variable i for their DO loops As a result the DO loop repeats only once in the main exec because the function returns to the main
207. is four Finding the Number of Elements In a Buffer To find out how many elements are in the most recently created buffer use the TSO E REXX QELEM command QELEM returns in the REXX special variable RC the number of elements in the most recently created buffer PUSH A MAKEBUF PUSH B PUSH C QELEM SAY The number of elements is RC RC 2 Chapter 11 Storing Information in the Data Stack 11 11 Creating a Buffer on the Data Stack QELEM does not return the number of elements on a data stack with no buffers created by the MAKEBUF command If QBUF returns 0 no matter how many elements are on the stack QELEM also returns 0 For more information about these stack commands see TSO E REXX Reference SC28 1975 Exercises Creating a Buffer on the Data Stack 1 What are the results of the following instructions a What is item QUEUE A QUEUE B MAKEBUF QUEUE C PULL item b What is element PUSH a PUSH b MAKEBUF PUSH c PUSH d DROPBUF PARSE PULL element c What is stackitem QUEUE a MAKEBUF QUEUE b MAKEBUF QUEUE c DROPBUF PULL stackitem d What is RC PUSH A MAKEBUF PUSH B CALL subl QBUF SAY RC EXIT subl MAKEBUF RETURN 11 12 05 390 V1R2 0 TSO E REXX User s Guide Creating a Buffer on the Data Stack e What is RC QUEUE A MAKEBUF PUSH B PUSH C MAKEBUF PUSH D QELEM SAY RC f What is RC QUEUE A Q
208. ise only when the exec is stored in either SYSPROC or the application level CLIST file using the ALTLIB command The compression removes comment text between the comment delimiters and removes leading and trailing blanks and replaces blank lines with null lines Blanks and comments within literal strings or DBCS strings are not removed If the system finds the characters SOURCELINE outside of a comment the exec is not compressed Additionally if you do not want an exec to be compressed you can allocate the exec to the CLIST user level file or any of the levels used for execs Improve performance Depending on your installation s setup you can affect the performance of execs you run by allocating the data sets that contain them to either SYSEXEC or SYSPROC More about this technique appears in the following sections on allocating to a specific system file Allocating to SYSEXEC SYSEXEC is a system file that can contain execs only SYSEXEC precedes SYSPROC in the search order Therefore execs in PDSs allocated to SYSEXEC are retrieved more rapidly than execs in PDSs allocated to SYSPROC Allocating to SYSPROC SYSPROC is a system file that originally contained only CLISTs written for applications or for an individual s use SYSPROC now can also contain execs as long as the execs are distinguishable from CLISTs The SYSEXEC file is searched first followed by SYSPROC If your installation uses a large number of CLISTs that are in
209. iteral string SAY This is a literal string This example appears on the screen as follows This is a literal string This is a literal string This is a literal string Continuing an instruction A comma indicates that the instruction continues to the next line Note that a space is added between extended and REXX when it appears on the screen SAY This is an extended REXX literal string This example appears on the screen as one line This is an extended REXX literal string 2 4 OS 390 V1R2 0 TSO E REXX User s Guide Syntax of REXX Instructions Also note that the following two instructions are identical and yield the same result when displayed on the screen SAY This is a string is functionally identical to SAY This is a string These examples appear on the screen as This is a string In the first example the comma at the end of line 1 adds a space when the two lines are concatenated for display In the second example the space between the two separate strings is preserved when the line is displayed Continuing a literal string without adding a space f you need to continue an instruction to a second or more lines but do not want REXX to add spaces when the line appears on the screen use the concatenation operand two single OR bars SAY This is an extended literal string that is bro ken in an awkward place This example appears on the screen as one line with
210. ive OR 3 10 exec allocating to a file 2 12 comment line 2 2 description xiii 2 2 editing in ISPF A 7 example 2 2 identifying as an exec 2 2 interactive 2 3 invoking a CLIST 13 5 invoking as acommand 8 5 passing information to 2 16 prompting a user for input to a TSO E command 8 4 prompting the user for input to a TSO E command 10 7 11 16 receiving input 2 17 returning information to a CLIST 13 6 running error message 2 13 explicitly 2 10 13 3 from a CLIST 13 4 13 5 from another exec 13 3 implicitly 2 12 13 3 A 1 implicitly with ALTLIB B 1 in a TSO E address space 13 3 in non TSO E address space 13 8 in the background 13 7 in the foreground 13 3 where to run 2 11 with 2 13 with IKJEFTO1 13 7 with IRXEXEC 13 8 with IRXJCL 13 8 with JCL 13 7 service available 13 1 Index X 3 exec continued using blank line 2 8 using double byte character set names 2 9 writing 2 2 EXEC command 2 11 2 17 11 16 prompt option 8 4 with data set name as argument 8 2 exec identifier 2 2 2 8 13 4 EXECIO command adding information to a data set 12 9 copying information to a data set 12 8 copying information to and from compound variables 12 10 description 12 3 example 12 13 reading information from a data set 12 8 return code 12 7 updating information to a data set 12 10 writing information to a data set 12 6 EXECUTIL HI command 4 10 EXECUTIL SEARCHDD 13 4 EXECUTIL TE command 9 8 EXECUTIL TS command 9 4 9 5 EXIT instruction 4 2
211. k ADDRESS LINKMVS proca29 line len linel_ lt v a l u e gt FREE FI INDD EXIT 0 Running an Exec After you have placed REXX instructions in a data set you can run the exec explicitly by using the EXEC command followed by the data set name and the exec keyword operand or implicitly by entering the member name You can run an exec implicitly only if the PDS that contains it was allocated to a system file More information about system files appears in the Running an Exec Implicitly on page 2 12 2 10 09 390 V1R2 0 TSO E REXX User s Guide Running an Exec Running an Exec Explicitly The EXEC command runs non compiled programs in TSO E To run an exec explicitly enter the EXEC command followed by the data set name that contains the exec and the keyword operand exec to distinguish it from a CLIST You can specify a data set name according to the TSO E data set naming conventions in several different ways For example the data set name USERID REXX EXEC TIMEGAME can be specified as A fully qualified data set which appears within quotation marks EXEC userid rexx exec timegame exec A non fully qualified data set which has no quotation marks can eliminate your profile prefix usually your user ID as well as the third qualifier exec EXEC rexx exec timegame exec eliminates prefix EXEC rexx timegame exec eliminates prefix and exec For information about other ways to specify a data set name see th
212. k kk k k k k kk k k k kkk kkk k kkk kk window_seats 0 Initialize window seats to 0 x passenger 0 Initialize passengers to 0 DO UNTIL passenger gt 8 window seats 4 BRK RA RR REA KR RRA RRR EA KKK ERK ERIK k k k k kk k k k k k k k kk AEE k k kkk kkk Continue until you have questioned all 8 passengers or until all the window seats are taken x BRK seek kek k ke k k kke k k k e kek k ke k k k k k k k k k k k k k k kk k k k k kk k k kk kkk k k kkk kkk SAY Do you want a window seat Please answer Y or N PULL answer passenger passenger 1 Increase the number of passengers by 1 IF answer Y THEN window seats window seats 1 Increase the number of window seats by 1 ELSE NOP END SAY window seats window seats were assigned SAY passenger passengers were questioned Combining Types of Loops You can combine repetitive and conditional loops to create a compound loop The following loop is set to repeat 10 times while a certain condition is met at which point it stops quantity 20 DO number 1 TO 10 WHILE quantity 50 quantity quantity number SAY Quantity quantity END Loop number Chapter 4 Controlling the Flow Within an Exec 4 17 Using Looping Instructions The result of this example is as follows Quantity 21 Loop 1 Quantity 23 Loop 2 Quantity 26 Loop 3 Quantity 30 Loop 4 Quantity 35 Loop 5 Quanti
213. k kkk kkk kkk kkk kkk kkk kkk kkk kkk k REXX RR RRR RK RRR RRR k k k k RE kkk k ERE RE This exec prints data sets named by a user until the user enters a null line EK kk k k k e k e e k e kek k k k e kk e ke k k kk RIK KERRI KEK k k k kk k k k k kk k k k k kk kkk k kkk kk DO FOREVER SAY Enter the name of the next data set or a blank to end PULL dataset_name IF dataset_name THEN EXIT ELSE DO PRINTDS DA dataset name SAY dataset name printed END END This example sends data sets to the printer and then issues a message that the data set was printed When the user enters a blank the loop ends and so does the exec To end the loop without ending the exec use the LEAVE instruction as described in the following topic Chapter 4 Controlling the Flow Within an Exec 4 11 Using Looping Instructions LEAVE Instruction The LEAVE instruction causes an immediate exit from a repetitive loop Control goes to the instruction following the END keyword of the loop An example of using the LEAVE instruction follows r Example Using the LEAVE Instruction kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX XK kkk kkk RR RR kkk kkk ERE kk This exec uses the LEAVE instruction to exit from a DO FOREVER loop that sends data sets to the printer x RR RR RRR RRR RRR ERK KERIKERI AKER AKER KI KEK IK KKK IK KKK IKARIA k kk k ERR DO FOREVER SAY Enter the name of the next data set SAY When there
214. kkk kk This exec runs another exec implicitly and then sends a message when the called exec finishes It receives as an argument the name of a PDS member to run It activates the system procedure file SYSEXEC allocates the data set to SYSEXEC pushes some x commands on the data stack and then implicitly executes the exec RR kk RR RRR e e e ERR RR ERIK KERIKERI KEIR KIKI KK KR II k k k kk kkk k kkk kk ARG dsn EXECUTIL SEARCHDD yes Establish the system library SYSEXEC PUSH SEND Sequence over USER Put a message on the stackx PUSH TIME Push the time command PUSH FREE F SYSEXEC Push command to free SYSEXEC PARSE VAR dsn name member Separate the data set name from the member name ALLOC DA name F SYSEXEC SHR REUSE execname STRIP member t Remove the last parentheses from the member name x PUSH execname Put the member name on the stack RR RR RRR RRR REE K RRR RIKKI KERIKERI AKER AK KKK KKK EA k k k kk kkk k kkk kk The output from this exec depends on the exec that it runs x Output can be as follows x TIME 01 23 56 PM CPU 00 00 23 SERVICE 297798 SESSION 04 15 20 MAYx 12 1989 Sequence over USERID x READY K kk k k e e ek e ke e e kek k k ke e kk de k k k kk k k k e k k k k AKER k k k kk k k k k kk k k k k kk kkk k kkk kk 11 18 05 390 V1R2 0 TSO E REXX User s Guide Types
215. lation for REXX libraries and include the record format RECFM record length LRECL and block size BLKSIZE from the appropriate system file from the Preliminary Checklist on page A 4 If you are unsure about which system file is appropriate use the values from SYSEXEC If your installation has no attribute recommendations and you have no attributes from the Preliminary Checklist you can use the following attributes on the ISPF PDF Allocate New Data Set panel T 2 2 ALLOCATE NEW DATA SET COMMAND gt DATA SET NAME USERID REXX EXEC VOLUME SERIAL gt Blank for authorized default volume GENERIC UNIT gt Generic group name or unit address SPACE UNITS gt blks BLKS TRKS or CYLS PRIMARY QUAN gt 50 in above units SECONDARY QUAN gt 20 in above units DIRECTORY BLOCKS gt 10 Zero for sequential data set RECORD FORMAT gt VB RECORD LENGTH gt 255 BLOCK SIZE gt 6120 EXPIRATION DATE gt YY MM DD YY DDD in julian form DDDD for retention period in days or blank Only one of these fields may be specified as A 6 09 390 V1R2 0 TSO E REXX User s Guide 4 Edit a member of the newly created PDS by selecting the EDIT option option 2 and specifying the PDS name with a member name After you have allocated a PDS you can press the RETURN PF key PF4 to return to the Primary Option Menu and begin a
216. lifier any name as the second qualifier and preferably exec as the third qualifier You can allocate the PDS with the Utilities option in ISPF PDF or with the TSO E ALLOCATE command For specific information about allocating a data set for an exec see Appendix A Allocating Data Sets on page A 1 What is a REXX Exec A REXX exec consists of REXX language instructions that are interpreted directly by the REXX interpreter or compiled directly by a REXX language compiler and executed by a compiler runtime processor An exec can also contain commands that are executed by the host environment An advantage of the REXX language is its similarity to ordinary English This similarity makes it easy to read and write a REXX exec For example an exec to display a sentence on the screen uses the REXX instruction SAY followed by the sentence to be displayed r Example of a Simple Exec kk kkk kkk kkk kkk kkk kk RIKER REX XK RRR RR RRR RRR KR RRR RR k k RARER ERR ER SAY This is a REXX exec Note that this simple exec starts with a comment line to identify the program as a REXX exec A comment begins with and ends with To prevent incompatibilities with CLISTs IBM recommends that all REXX execs start with a comment that includes the characters REXX within the first line line 1 of the exec Failure to do so can lead to unexpected or unintended results in your REXX exec More about comments and why you might need
217. lish the allocation is to write a setup exec that automatically executes when you log on Information about how to write a setup exec is in Checklist 3 on page A 10 and Checklist 4 on page A 12 If you do not know which checklist to use use Checklist 3 The following checklists assume that the defaults shipped with TSO E have not been altered by your installation Also if your installation changes system allocations after you have used the checklists to set up your private allocation you might need to use the checklists again to keep your allocations up to date A 2 OS 390 V1R2 0 TSO E REXX User s Guide Preliminary Checklist 1 Issue the LISTALC STATUS command to see the names of all data sets allocated to SYSEXEC and SYSPROC To see what data sets are already defined to SYSEXEC and SYSPROC at your installation issue the LISTALC command with the STATUS keyword READY hp2 listalc status You then see several screens of data set names that might look something like the following Scroll until you find SYSEXEC and SYSPROC DDNAME DISP ICQ INFOCTR LOAD STEPLIB KEEP CATALOG VTS0022 SYS00006 KEEP KEEP CATALOG VTS0028 KEEP KEEP ISP PHONE EXEC SYSEXEC KEEP ICQ INFOCTR ICQCLIB SYSPROC KEEP SYS1 TSO CLIST KEEP ISP ISPF CLISTS KEEP In this example one data set ISP PHONE EXEC is allocated to SYSEXEC and three data sets ICQ INFOCTR ICQCLIB SYS1 TSO CLIST and ISP ISPF CLISTS are allocated to SYSPROC When a
218. lly qualified data set name be sure to enclose it in two sets of quotation marks as follows one set to define it as a literal string to REXX and the other to indicate a fully qualified data set to TSO E x LISTDSI proj5 rexx exec x is set to a function code or 10 2 05 390 V1R2 0 TSO E REXX User s Guide TSO E External Functions x LISTDSI proj5 rexx exec x is set to a function code When you specify a data set name that begins with your prefix usually your user ID you can use one set of quotation marks to define it as a literal string or no quotation marks TSO E adds your prefix to the data set name whether or not it is enclosed within a set of quotation marks x LISTDSI my data x is set to a function code x LISTDSI my data x is set to a function code When you specify a variable that was previously set to a data set name do not enclose the variable in quotation marks Quotation marks would prevent the data set name from being substituted for the variable name variable my data x LISTDSI variable You cannot use LISTDSI with the filename parameter if the filename is allocated to a data set which exists more than once with the same name on different volumes and which is already in use because in this case the system may not retrieve information for the data set you wanted After LISTDSI executes the function call is replaced by one of the following function codes
219. lution usum RE Rnd AU WR uM RU e Baw 1 3 Benefits of Using a Compiler 20200200005 1 3 Improved Performance 000000 eee eee 1 4 Reduced System Load 0 2 2 0 000 les 1 4 Protection for Source Code and Programs 1 4 Improved Productivity and Quality 1 4 Portability of Compiled Programs s 1 4 SAA Compliance Checking 22 llle 1 5 Chapter 2 Writing and Running a REXX Exec 2 1 Before You Begin llle 2 1 What is a REXX Exec aaua aaa s 2 2 Syntax of REXX Instructions 0 000000 ens 2 3 The Character Type of REXX Instructions 2 3 The Format of REXX Instructions 2 2 4 Types of REXX Instructions oos 2 6 Execs Using Double Byte Character Set Names 2 9 Running an Exec s 2 10 Running an Exec Explicitly els 2 11 Running an Exec Implicitlly een 2 12 Interpreting Error Messages oll 2 13 Preventing Translation to Uppercase 2 14 Passing Information to an Exec aaa 2 16 Copyright IBM Corp 1988 1996 iii Preventing Translation of Input to Uppercase 2 18 Passing Arguments aaae ss 2 19 Chapter 3 Using Variables and Expressions 3 1 Using Varlables etn ark Se EO RAR ER DD eee BE EE 3 2 Using Expressions ls 3 4
220. making unauthorized changes to your programs You can distribute your REXX programs in object code only Load modules can be further protected by using a security server such as RACF Improved Productivity and Quality The Compiler can produce source listings cross reference listings and messages which help you more easily develop and maintain your REXX programs The Compiler identifies syntax errors in a program before you start testing it You can then focus on correcting errors in logic during testing with the REXX interpreter Portability of Compiled Programs A REXX program compiled under MVS ESA can run under CMS Similarly a REXX program compiled under CMS can run under MVS ESA 1 4 0S 390 V1R2 0 TSO E REXX User s Guide Benefits of Using a Compiler SAA Compliance Checking The Systems Application Architecture SAA definitions of software interfaces conventions and protocols provide a framework for designing and developing applications that are consistent within and across several operating systems The SAA Procedures Language is a subset of the REXX language supported by the interpreter under TSO E and can be used in this operating environment To help you write programs for use in all SAA environments the Compiler can optionally check for SAA compliance With this option in effect a warning message is issued for each non SAA item found in a program For more information see BM Compiler and Library for REXX 370 I
221. ments to stacks and queues Elements can be placed on the top or the bottom of a data stack Removal of elements from the data stack however occurs from the top of the stack only v4 Data Stack Manipulating the Data Stack There are several REXX instructions that manipulate the data stack Two instructions add elements to the data stack and another removes elements from the data stack Adding Elements to the Data Stack You can store information on the data stack with two instructions PUSH and QUEUE PUSH puts one item of data on the top of the data stack There is virtually no limit to the length of the data item eleml String 1 for the data stack PUSH eleml QUEUE puts one item of data on the bottom of the data stack Again there is virtually no limit to the length of the data item elemA String A for the data stack QUEUE elemA If the two preceding sets of instructions were in an exec the data stack would appear as follows PUSH A QUEUE 11 2 09 390 V1R2 0 TSO E REXX User s Guide Manipulating the Data Stack Note Some people find it less confusing when adding elements in a particular order to the data stack to consistently use the same instruction either PUSH or QUEUE but not both Removing Elements from the Stack To remove information from the data stack use the PULL and PARSE PULL instructions the same instructions used previously in this book to extract information from the termin
222. message that the attention facility displays ENTER HI TO END A NULL LINE TO CONTINUE OR AN IMM ts EDIATE COMMAND The type of tracing is the same as that initiated by issuing the EXECUTIL TS command 9 6 05 390 V1R2 0 TSO E REXX User s Guide Debugging Execs Options Within Interactive Trace When you are operating in the interactive debug facility you have several options during the pauses that occur between each traced instruction You can Continue tracing by entering a null line Type one or more additional instructions to be processed before the next instruction is traced Enter an equal sign 2 to re execute the last instruction traced End interactive tracing as described in the next topic Continuing Interactive Tracing To continue tracing through an exec simply press the Enter key to enter a null line during the pause between each traced instruction The next traced instruction then appears on the screen Repeatedly pressing the Enter key therefore takes you from pause point to pause point until the exec ends Typing Additional Instructions to be Processed During the pause between traced instructions you can enter one or more instructions that are processed immediately The instruction can be any type of REXX instruction including a command or invocation to another exec or CLIST You can also enter a TRACE instruction which alters the type of tracing After you enter the instruction you might ne
223. n a value to the invoker of the exec If the exec was invoked as a subroutine from another REXX exec the value is received in the REXX special variable RESULT If the exec was invoked as a function the value is received in the original expression at the point where the function was invoked Otherwise the value is received in the REXX special variable RC The value can represent a return code and can be in the form of a constant or an expression that is computed r Example Using the EXIT Instruction kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REXX RRR RRR RR RRR RRR KERR RR ER EER This exec uses the EXIT instruction to end the exec and return a value that indicates whether or not a job applicant gets the job A value of 0 means the applicant does not qualify for x the job but a value of 1 means the applicant gets the job The value is placed in the REXX special variable RESULT x RR RAR RRR ER RRR ERR RR k RIKKI A KERIKERI KEI k KKK k k KKK IAA k kk kkk k kk k kk SAY How many months of experience do you have Please enter SAY the months as a number PULL month SAY Can you supply 3 references Please answer Y or N PULL reference SAY Are you available to start work tomorrow Please answer Y or N PULL tomorrow IF month gt 24 amp reference Y amp tomorrow Y THEN job 1 person gets the job ELSE job 0 person does not get the job EXIT job 4 20 095 390 V1
224. n edit session Select the EDIT option option 2 from the ISPF PDF Primary Option Menu Enter END command ISPF PDF PRIMARY OPTION MENU OPTION gt 2 USERID YOURID 0 ISPF PARMS Specify terminal and user parameters TIME 12 47 1 BROWSE Display source data or output listings TERMINAL 3277 2 EDIT Create or change source data PF KEYS 12 3 UTILITIES Perform utility functions 4 FOREGROUND Invoke language processors in foreground 5 BATCH Submit job for language processing 6 COMMAND Enter TSO command or CLIST 7 DIALOG TEST Perform dialog testing 8 LM UTILITIES Perform library administrator utility functions 9 IBM PRODUCTS Additional IBM program development products C CHANGES Display summary of changes for this release T TUTORIAL Display information about ISPF PDF X EXIT Terminate ISPF using log and list defaults to terminate ISPF Then specify the data set name and member name on the Edit Entry Panel In the example that follows the member name is timegame DATA SET NAME VOLUME SERIAL PROFILE NAME INITIAL MACRO FORMAT NAME OTHER PARTITIONED OR DATA SET PASSWORD COMMAND gt ISPF LIBRARY PROJECT gt userid GROUP gt rexx gt gt gt TYPE gt exec MEMBER gt timegame Blank for member selection list gt If not cataloged If password protected Blank defaults to data set t
225. name and job name should be excluded from display of retrieved messages 10 12 05 390 V1R2 0 TSO E REXX User s Guide Additional Examples Additional Examples Example 1 Using the LISTDSI and SYSDSN Functions RR kkk kk RRR RRR ERR RR ER kkk kkk kkk REX X RR RRR RRR KERR RK KEK k k k KARR RRR ERE This exec reallocates a data set with more space It receives as arguments the names of a base data set and a new data set X It uses the SYSDSN function to ensure the base data set exists uses the LISTDSI function to set variables with attributes of X the base data set doubles the primary space variable and then uses the variables as input to the ALLOCATE command to x reallocate a new data set x RR RRR RRR IRR REE RRR ERIK KERIKERI RRA AK KR k k k k kk k k k k kk kkk k kkk kk PARSE ARG baseds newds Receive the data set names with quotes if any x IF SYSDSN baseds OK THEN DO If the base data set exists x LISTDSI baseds use the LISTDSI function IF x 0 THEN If the function code is 0 CALL alc call an internal subroutine ELSE DO Else display the system x SAY sysmsglvl1 messages and codes for LISTDS SAY sysmsglvl2 SAY Function code from LISTDSI is x SAY Sysreason code from LISTDSI is sysreason END END ELSE SAY Data set baseds not found EXIT alc newprimary 2 sysprimary Compute new primary space x
226. names To use DBCS names you must code OPTIONS ETMODE as the first instruction in the exec ETMODE specifies that those strings that contain DBCS characters are to be checked as being valid DBCS strings DBCS characters must be enclosed within shift out X OE and shift in X OF delimiters In the following example the shift out SO and shift in SI delimiters are represented by the less than symbol lt and the greater than symbol gt respectively For example lt S Y M D gt and lt D B C S R T N gt represent DBCS symbols in the following examples Example 1 The following is an example of an exec using a DBCS variable name and a DBCS subroutine label REXX OPTIONS ETMODE ETMODE to enable DBCS variable names j 1 lt S Y M D gt 10 Variable with DBCS characters between shift out lt and shift in gt CALL D B C S R T N Invoke subroutine with DBCS name lt D B C S R T N gt Subroutine with DBCS name DO i 1 TO 10 IF x i lt S Y D M gt THEN Does x i match the DBCS variable s value SAY Value of the DBCS variable is lt S Y D M gt END EXIT 0 1 The SO and SI characters are non printable Chapter 2 Writing and Running a REXX Exec 2 9 Running an Exec Example 2 The following example shows some other uses of DBCS variable names with the EXECIO stem option as DBCS parameters passed to a program invoked through LINKMVS and with built in functi
227. ncatenation can be significant in formatting output The operators that indicate how to join two terms are as follows Operator Meaning blank Concatenate terms and place one blank in between Terms that are separated by more than one blank default to one blank when read For example SAY true blue result is TRUE BLUE ll Concatenate terms and place no blanks in between For example 8 2YL C 3 result is 49 x abuttal Concatenate terms and place no blanks in between For example per_cent if per cent 50 result is 50 Using Concatenation Operators One way to format output is to use variables and concatenation operators as in the following example A more sophisticated way to format information is with parsing and templates Information about parsing appears in Parsing Data on page 7 4 r Example using Concatenation Operators kk kkk kkk kkk kkk kkk kk kkk kkk k kkk REXX deeeeietekekekoekekejekdetekekekekdekekekekeeieiee This exec formats data into columns for output EK kk k k e e ek de e e e kek k k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk sport base equipment ball column i cost 5 SAY sport equipment column cost The result of this example is baseball 5 Priority of Operators When more than one type of operator appears in an expression what operation does the language processor do first IF A gt
228. nd environment The language processor environment is the environment in which a REXX exec runs The host command environment is the environment to which the language processor passes commands for execution The valid host command environments are defined by the language processor environment For more information about defining language processor environments see TSO E REXX Reference SC28 1975 Customizing a Language Processor Environment An individual or an installation can customize a language processor environment in two ways Change the values in the three default parameters modules IRXTSPRM IRXISPRM and IRXPARMS e Call an initialization routine IRXINIT and specifying parameters to change default parameters For more information about customizing a language processor environment see TSO E REXX Reference SC28 1975 13 12 05 390 V1R2 0 TSO E REXX User s Guide Part 3 Appendixes Copyright IBM Corp 1988 1996 OS 390 V1R2 0 TSO E REXX User s Guide What is Allocation Appendix A Allocating Data Sets What is Allocation es A 1 Where TOBON i sx bee tac x9 be ee Paw eke X A 2 Preliminary Checklist 22e A 3 Checklist 1 Creating and Editing a Data Set Using ISPF PDF A 5 Checklist 2 Creating a Data Set with the ALLOCATE Command A 9 Checklist 3 Writing an Exec that Sets up Allocation to SYSEXEC A 10 Checklist 4 Writing an Exec that Sets up Allocation to SYSPR
229. nd environment 8 7 8 9 M MAKEBUF command 11 10 message error 2 13 2 14 getting more information 2 14 explanation 2 14 interpreting 2 13 tracing 3 14 MFJOB 10 12 MFOSNM 10 12 MFSNMJBX 10 12 MFTIME 10 12 move information from one data set to another 12 8 MVS batch comparison to TSO E background 13 11 running an exec 13 8 using IRXJCL 13 8 using the data stack 13 10 MVS host command environment 8 6 MVSVAR external function 10 5 N name for variable restriction on naming 3 2 valid name 3 2 NEWSTACK command 11 15 non TSO E address space running an exec 13 8 null instruction 2 8 numeric constant decimal number 3 4 floating point number 3 4 signed number 3 4 whole number 3 4 O operator arithmetic 3 4 order of priority 3 6 Boolean 3 10 comparison 3 7 concatenation 3 12 logical 3 10 order of priority 3 12 OUTTRAP external function 10 6 P parameter See argument parentheses 8 2 PARSE ARG instruction 7 5 PARSE EXTERNAL instruction 11 5 PARSE instruction preventing translation to uppercase 2 15 2 18 PARSE PULL instruction 7 4 11 3 PARSE UPPER ARG instruction 7 5 PARSE UPPER PULL instruction 7 4 PARSE UPPER VALUE instruction 7 5 PARSE UPPER VAR instruction 7 5 PARSE VALUE WITH instruction 7 5 PARSE VAR instruction 7 5 parsing description 7 4 instruction ARG 7 4 PARSE ARG 7 5 PARSE PULL 7 4 PARSE UPPER ARG 7 5 PARSE UPPER PULL 7 4 PARSE UPPER VALUE 7 5 PARSE UPPER VAR 7 5 PARSE VALUE
230. nds to Prompt the User 8 4 Invoking Another Exec as a Command 8 5 Issuing Other Types of Commands from an Exec 8 6 What is a Host Command Environment 8 6 Changing the Host Command Environment 8 11 Chapter 9 Diagnosing Problems Within an Exec 9 1 Debugging Execs ler s 9 1 Tracing Commands with the TRACE Instruction 9 2 Using REXX Special Variables RC and SIGL 9 3 Tracing with the Interactive Debug Facility 9 4 Chapter 10 Using TSO E External Functions 10 1 TSO E External Functions 2n 10 1 Using the GETMSG Function 0 2 002000 10 2 Using the LISTDSI Function 10 2 Using the MSG Function l llle 10 4 Using the MVSVAR Function 2200 4 10 5 Using the OUTTRAP Function 220 10 6 Using the PROMPT Function es 10 7 Using the SETLANG Function 2 len 10 7 Using the STORAGE Function 10 8 Using the SYSCPUS Function 10 8 Using the SYSDSN Function llle 10 9 Using the SYSVAR Function loose 10 10 Additional Examples s 10 13 Function Packages s 10 17 Search Order for Functions 2 2002000 10 17 Chapter 11 Storing Information in the Data Stack 11
231. ned a value the variable displays the value of its own name translated to uppercase In the following example if the variable new was not assigned a previous value the word NEW is displayed SAY new displays NEW Exercises Identifying Valid Variable Names Which of the following are valid REXX variable names 1 8eight 2 25 00 3 MixedCase Chapter 3 Using Variables and Expressions 3 3 Using Expressions 4 nine_to_five 5 result ANSWERS 1 Invalid because the first character is a number 2 Valid 3 Valid 4 Valid 5 Valid but it is a reserved variable name and we recommend that you use it only to receive results from a subroutine Using Expressions An expression is something that needs to be calculated and consists of numbers variables or strings and one or more operators The operators determine the kind of calculation to be done on the numbers variables and strings There are four types of operators arithmetic comparison logical and concatenation Arithmetic Operators Arithmetic operators work on valid numeric constants or on variables that represent valid numeric constants Types of Numeric Constants 12 A whole number has no decimal point or commas Results of arithmetic operations with whole numbers can contain a maximum of nine digits unless you override the default with the NUMERIC DIGITS instruction For information about the NUMERIC DIGITS instruction see TSO E REXX Referen
232. nformation it is not changed to uppercase quote Knowledge is power PARSE VAR quote wordl word2 word3 wordl contains Knowledge word2 contains is word3 contains power The PARSE UPPER VAR instruction changes character information to uppercase before putting it into the variables quote Knowledge is power PARSE UPPER VAR quote wordl word2 word3 wordl contains KNOWLEDGE word2 contains IS word3 contains POWER For more information about parsing instructions see TSO E REXX Reference SC28 1975 PARSE VALUE WITH Instruction The PARSE VALUE WITH instruction parses a specified expression such as a literal string into one or more variable names that follow the WITH subkeyword If the literal string contains character information it is not changed to uppercase PARSE VALUE Knowledge is power WITH wordl word2 word3 wordl contains Knowledge word2 contains is word3 contains power The PARSE UPPER VALUE instruction changes character information to uppercase before assigning it to the variable names PARSE UPPER VALUE Knowledge is power WITH wordl word2 word3 wordl contains KNOWLEDGE word2 contains IS word3 contains POWER Chapter 7 Manipulating Data 7 5 Parsing Data Ways of Parsing Parsing separates data by comparing the data to a template or pattern of variable names Separators in a template can b
233. no change If there isa change to the line the user types the entire line with the x change and the new line is returned to the data set x KR KKK je dede eee dede je kde dee kk K k e k je ke eek k k k k k k k k kk k k k k kk k k k k kk k kk PARSE ARG name numlines Get data set name and size from user ALLOC DA name F updatedd OLD eof NO Initialize end of file flag DO i 1 to numlines WHILE eof NO EXECIO 1 DISKRU updatedd Queue the next line on the stack IF RC 2 THEN Return code indicates end of file eof YES ELSE DO PARSE PULL line SAY Please make changes to the following line SAY If you have no changes press ENTER SAY line PARSE PULL newline IF newline THEN NOP ELSE DO PUSH newline EXECIO 1 DISKW updatedd END END END 12 12 05 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information Additional Examples r EXECIO Example 1 kkkkkkkkkkkkkkkkkkkkkkkkkkkkx REXX RRR kk RRR kkk k kkk kk kkk k kkk ERE kk This exec reads from the data set allocated to INDD to find the first occurrence of the string Jones Upper and lowercase x distinctions are ignored K kk k k e e eke e e e e kek k ke k e kk e ke e k kk k k k e RIA KEK IK KKK k k k k kk k k k k kk k kk k kkk kk done no lineno 0 DO WHILE done no EXECIO 1 DISKR indd IF RC 0 THEN Record was read DO PULL record lineno lin
234. nput string centered in it with pad characters added as necessary to make up the length COPIES Returns the specified number of concatenated copies of the input string FORMAT Returns the input number rounded and formatted JUSTIFY Returns a specified string formatted by adding pad characters between words to justify to both margins LEFT Returns a string of the specified length truncated or padded on the right as needed RIGHT Returns a string of the specified length truncated or padded on the left as needed SPACE Returns the words in the input string with a specified number of pad characters between each word Chapter 5 Using Functions 5 5 Built In Functions String Manipulating Functions Function Description ABBREV Returns a string indicating if one string is equal to the specified number of leading characters of another string DELSTR Returns a string after deleting a specified number of characters starting at a specified point in the input string DELWORD Returns a string after deleting a specified number of words starting at a specified word in the input string FIND Returns the word number of the first word of a specified phrase found within the input string INDEX Returns the character position of the first character of a specified string found in the input string INSERT Returns a character st
235. nstruction PARSE PULL dataset name ANSWERS 1 The results of the repetitive loops are as follows a 1 2 3 Digit is now 4 b 10 8 6 Count is now 4 C blank Index is now 10 2 The user would be unable to leave the loop because Quit is not equal to QUIT In this case omitting the PARSE keyword is preferred because regardless of whether the user enters quit QUIT or Quit the language processor translates the input to uppercase before comparing it to QUIT Chapter 4 Controlling the Flow Within an Exec 4 13 Using Looping Instructions Conditional Loops There are two types of conditional loops DO WHILE and DO UNTIL Both types of loops are controlled by one or more expressions However DO WHILE loops test the expression before the loop executes the first time and repeat only when the expression is true DO UNTIL loops test the expression after the loop executes at least once and repeat only when the expression is false DO WHILE Loops DO WHILE loops in a flowchart appear as follows I True expression gt __ instruction s False DO WHILE END As REXX instructions the flowchart example looks like DO WHILE expression expression must be true instruction s END Use a DO WHILE loop when you want to execute the loop while a condition is true DO WHILE tests the condition at the top of the loop If the condition is initially false the loop is never executed
236. nstruction can be used with the SAY instruction to interact with a user at the terminal Note To prevent the language processor from searching the data stack you can issue the PARSE EXTERNAL instruction instead of PULL PARSE EXTERNAL gets input directly from the terminal and bypasses the data stack e Responses to commands A TSO E interactive command such as LISTDS TRANSMIT and ALLOCATE can prompt a terminal user for information Similarly user responses can be put on the data stack by an exec for the command s use Chapter 11 Storing Information in the Data Stack 11 5 Using the Data Stack Commands to be issued after the exec ends When an exec ends all elements remaining on the data stack are processed before the READY mode message is displayed These remaining elements are treated as TSO E commands to be issued If the element is not a TSO E command or an implicit exec or CLIST to be run you see the message eer command_name NOT FOUND Information the EXECIO command reads from and writes to data sets when performing I O For information about the EXECIO command and how it uses the data stack see Using EXECIO to Process Information to and from Data Sets on page 12 2 Using the Data Stack The data stack has some unique characteristics such as It can contain a virtually unlimited number of data items of virtually unlimited size It can contain commands to be issued after the exec ends It can
237. nterpreted language TSO E implements the REXX language as an interpreted language When a REXX exec runs the language processor directly processes each language statement Languages that are not interpreted must be compiled into machine language and possibly link edited before they are run You can use the IBM licensed product IBM Compiler and Library for REXX 370 to provide this function Extensive parsing capabilities REXX includes extensive parsing capabilities for character manipulation This parsing capability allows you to set up a pattern to separate characters numbers and mixed input Components of REXX The various components of REXX are what make it a powerful tool for programmers REXX is made up of Instructions There are five types of instructions All but commands are processed by the language processor Keyword Assignment Label Null Command both TSO E REXX commands and host commands Built in functions These functions are built into the language processor and provide convenient processing options TSO E external functions These functions are provided by TSO E and interact with the system to do specific tasks for REXX e Data stack functions A data stack can store data for I O and other types of processing 1 2 09 390 V1R2 0 TSO E REXX User s Guide Benefits of Using a Compiler The SAA Solution The SAA solution is based on a set of software interfaces co
238. ntly executed command SYSSCMD Name of most recently executed subcommand Argument Value Description SYSCPU Number of CPU seconds used during session in the form seconds hundredths of seconds SYSHSM Level of Data Facility Hierarchical Storage Manager DFHSM installed SYSJES Name and level of JES installed SYSLRACF Level of RACF installed SYSRACF Whether RACF is available SYSNODE Network node name of the installation s JES SYSSRV Number of system resource manager SRM service units used during session SYSTERMID Terminal ID of the terminal where the REXX exec was started SYSTSOE Level of TSO E installed in the form version release modification number Chapter 10 Using TSO E External Functions 10 11 TSO E External Functions Console Session Information Argument Value Description SOLDISP Whether solicited messages command responses should be displayed at terminal UNSDISP Whether unsolicited messages should be displayed at terminal SOLNUM The number of solicited messages command responses to be held in message table UNSNUM The number of unsolicited messages to be held in message table MFTIME Whether time stamp should be displayed with messages MFOSNM MFJOB Whether originating system name should be displayed with messages Whether originating job name or job ID should be displayed with messages MFSNMJBX Whether system
239. ntroducing the Next Step in REXX Programming Chapter 1 Introduction 1 5 Benefits of Using a Compiler 1 6 0S 390 V1R2 0 TSO E REXX User s Guide Before You Begin Chapter 2 Writing and Running a REXX Exec Before You Begin 2 2 ee 2 1 What is a REXX Exec oll 2 2 Syntax of REXX Instructions 2 000000 020008 2 3 The Character Type of REXX Instructions 2 3 Using Quotation Marks in an Instruction 2 3 The Format of REXX Instructions lens 2 4 Beginning an instruction oen 2 4 Continuing an instruction 2 200000 20005 2 4 Continuing a literal string without adding a space 2 5 Ending an instruction 0 00 00 eee ee e E aa 2 5 Types of REXX Instructions ees 2 6 KeyWord aues a Pare bah osos oko ek ROAST vog UR 6n wo od 2 7 ASsignment iuc ado de event ha va sux d 2 7 babel 0d km nt dr EROS RUE ES do E Re UU Ros dem S a h 2 8 Null a une desir eem ede qv ded tok n ers di dob ut 2 8 Gommand uae Ra ee ORS wh ee ERR es 2 8 Execs Using Double Byte Character Set Names 2 9 Running an Exec 2 aaa a 2 10 Running an Exec Explicitly 2 2 0 0 20000 2 11 Running an Exec Implicitly 2 2 0 0 2 20004 2 12 Allocating a PDS to a System File 2 12 Exercises Running the Example Execs 2 13 Interpreting Error Messages
240. numberl displays 5 7 EXIT pass PROCEDURE EXPOSE number1 numberl 7 number2 5 RETURN number2 6 14 09 390 V1R2 0 TSO E REXX User s Guide Writing a Function For more information about the PROCEDURE instruction see TSO E REXX Reference SC28 1975 Passing Information by Using Arguments A way to pass information to either internal or external functions is through arguments You can pass up to 20 arguments separated by commas in a function call function argument1 argument2 argument3 Using the ARG Instruction The function can receive the arguments with the ARG instruction Arguments are also separated by commas in the ARG instruction ARG argl arg2 arg3 The names of the arguments on the function call and the ARG instruction do not have to be the same because information is not passed by argument name but by position The first argument sent becomes the first argument received and so forth You can also set up a template in the function call which is then used in the corresponding ARG instruction For information about parsing templates see Parsing Data on page 7 4 The following exec sends information to an internal function that computes the perimeter of a rectangle The function returns a value in the variable perim that is specified after the RETURN instruction The main exec uses the value in perim to replace the function call Example of an Internal Function PETERR T EER
241. numbers PULL numberl number2 sum numberl number2 SAY The sum of the two numbers is sum Note For the PULL instruction to extract information from the terminal the data stack must be empty More information about the data stack appears in Chapter 11 Storing Information in the Data Stack on page 11 1 2 16 0S 390 V1R2 0 TSO E REXX User s Guide Passing Information to an Exec Specifying Values when Invoking an Exec Another way for an exec to receive input is through values specified when you invoke the exec For example to pass two numbers to an exec named add using the EXEC command type EXEC rexx exec add 42 21 exec To pass input when running an exec implicitly simply type values words or numbers after the member name add 42 21 These values are called an argument For information about arguments see Passing Arguments on page 2 19 The exec add uses the ARG instruction to assign the input to variables as shown in the following example r Example of an Exec that Uses the ARG Instruction Ek kkk kk kkk kkk k kkk kk kkk kkk kkk REX XK RRR RRR RRR KERIKERI RRR RARER ERE RE This exec receives two numbers as input adds them and x displays their sum x RR RR RRR RRR REE kek RRR RIK e ke k k kk k k k e k k e k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk ARG number1 number2 sum numberl number2 SAY The sum of the two numbers is sum ARG ass
242. nventions and protocols that provide a framework for designing and developing applications The SAA Procedures Language has been defined as a subset of the REXX language Its purpose is to define a common subset of the language that can be used in several environments TSO E REXX is the implementation of the SAA Procedures Language on the MVS system The SAA solution Defines a common programming interface you can use to develop applications that can be integrated with each other and transported to run in multiple SAA environments Defines common communications support that you can use to connect applications systems networks and devices Defines a common user access that you can use to achieve consistency in panel layout and user interaction techniques e Offers some applications and application development tools written by IBM Several combinations of IBM hardware and software have been selected as SAA environments These are environments in which IBM will manage the availability of support for applicable SAA elements and the conformance of those elements to SAA specifications The SAA environments are the following e MVS TSO E CICS IMS e VM CMS Operating System 400 OS 400 Operating System 2 OS 2 Benefits of Using a Compiler The IBM Compiler for REXX 370 Program Number 5695 013 and the IBM Library for REXX 370 Program Number 5695 014 provide significant benefits for programmers during prog
243. of Processing Chapter 12 Processing Data and Input Output Processing Types of Processing eee eee 12 1 Dynamic Modification of a Single REXX Expression 12 2 Using the INTERPRET Instruction 12 2 Using EXECIO to Process Information to and from Data Sets 12 2 When to Use the EXECIO Command 0 4 12 2 Using the EXECIO Command 00 00000005 12 3 Reading Information from a DataSet 12 3 How to specify the number of lines to read 12 3 How to read the data set 0 4 12 4 How to access the dataset 12 4 Option of specifying a starting line number 12 4 Options for DISKR and DISKRU 2 ee en 12 5 Writing Information to a Data Set 0 12 6 How to specify the number of lines to write 12 6 How to access the dataset 12 7 Options for DIBKRW aaa aaa 12 7 Return Codes from EXECIO lll ln 12 7 When to Use the EXECIO Command llle 12 8 Copying Information From One Data Set to Another 12 8 Copying an entire dataset ollis 12 8 Copying a specified number of lines to a new dataset 12 9 Adding 5 lines to the end of an existing sequential dataset 12 9 Copying Information to and from a List of Compound Variables 12 10
244. of trapped command output to find lines 9 characters long or longer Check those lines for the word x SYSPROC until it is found or until all lines have been checked If SYSPROC is found the index is decreased one and the name of the first data set concatenated to SYSPROC is stored in variablex concat x RR kk RR RRR RRR deed ee k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk DO WHILE found NO amp i lt name 0 IF LENGTH name i gt 9 THEN IF SUBSTR name i 3 7 SYSPROC THEN DO found YES i i 1 concat END ELSE i i 1 ELSE i i 1 END name i 10 14 05 390 V1R2 0 TSO E REXX User s Guide Additional Examples r Example 2 Part 2 Using the OUTTRAP Function data set names to the one in variable concat IF found YES THEN DO WHILE i 3 lt name 0 ji i 3 IF SUBSTR name i 1 3 THEN DO i i 1 concat concat name i END ELSE i name 0 END ELSE NOP Allocate the new concatenation to SYSPROC ALLOC F sysproc DA addname concat SHR REUSE RR kk RRR RRR RRR ERR KR ERIK KERIKERI KEI KKK IKK k kk k k k k kk kkk k EERE When SYSPROC is found loop through data sets until another file name is encountered or until all lines are processed x EK kk k k e e ek e ke k e kk k k k e kk e k k k kk k k k k kk ke k k KER k k k kk k k k k kk k k k k kk k kk k kkk kk Chapter 10 Using TSO E
245. oke an exec from a high level language program running in an MVS address space use one of the exec processing routines IRXEXEC or IRXJCL If you use IRXEXEC you must specify parameters that define the exec to be run and supply other related information For more information see TSO E REXX Reference SC28 1975 You can also use an exec processing routine to invoke an exec in a TSO E address space Two reasons to use them in TSO E are To pass more than one argument to an exec When invoking an exec implicitly or explicitly you can pass only one argument string With IRXEXEC you can pass multiple arguments To call an exec from a program other than a CLIST or exec Using IRXJCL to Run an Exec in MVS Batch To run a REXX exec in MVS batch you must specify program IRXJCL in the JCL EXEC statement SYSEXEC is the default load DD Running an exec in MVS batch is similar in many ways to running an exec in the TSO E background however there are significant differences One major difference is that the exec running in MVS batch cannot use TSO E services such as TSO E commands and most of the TSO E external functions Additional similarities and differences appear in Summary of TSO E Background and MVS Batch on page 13 11 The following series of examples show how an MVS batch job named USERIDA invokes a REXX exec in a PDS member named USERID MYREXX EXEC JCLTEST The member name JCLTEST is specified as the first word after the PARM p
246. on LENGTH REXX OPTIONS ETMODE ETMODE to enable DBCS variable names ALLOC FI INDD DA DEPTA29 DATA SHR REU RRR ERA ok RIKKI KIKI KK KKK KIKI K A K k A k R A K R KA K K KKKA K KAKA KK KK K Use EXECIO to read lines into DBCS stem variables RRR k RR REAR RR RARER RRR KIRKE IKK IKK k k kk k k k k kk K KEK IKKE AKER EXECIO DISKR indd FINIS STEM d b c s s t e m IF rc 0 THEN if good return code from execio RRR RRR RRR RAKE RIA KERRI KERIKERI KK KKK k k k k k kk KKK ERIK ERIK EEA AREER Say each DBCS stem variable set by EXECIO E k e e k ke e e e e e e k ke k e ke ke e ke KEK AK k k k k e k RIK KKK kk k k k k kk k k k k kk k k kk kk kkk kk DO i 1 TO lt d b c s__ s t e m gt 0 SAY Line i gt d b c s s t e m i END linel v a l u e d b c s s t e m 1 line 1 value line len length linel v a 1 u e Length of line RRR RRR RRR RRR RAK RRR ER RRR ERIK EIR KIKI AREA k KERIKERI k k kk kk k kk Invoke LINKMVS command proca29 to process a line Two variable names are used to pass 2 parameters one of which is a DBCS variable name The LINKMVS host command environment routine will look up the value of the two variables and pass their values to the address LINKMVS command proca29 RRR k e k ek e ke e e ke e k e ke ek ke k e ke k k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k kkk kkk k
247. on option 3 2 From the ISPF PDF Primary Option Menu select the UTILITIES option option 3 and press the Enter key OPTION gt 3 ISPF PARMS BROWSE EDIT UTILITIES FOREGROUND BATCH COMMAND DIALOG TEST LM UTILITIES IBM PRODUCTS CHANGES TUTORIAL EXIT 2X C XO OO OY Oi 5 C 9 C25 C Enter END command USERID YOURID Specify terminal and user parameters TIME 12 47 Display source data or output listings TERMINAL 3277 Create or change source data PF KEYS 12 Perform utility functions Invoke language processors in foreground Submit job for language processing Enter TSO command or CLIST Perform dialog testing Perform library administrator utility functions Additional IBM program development products Display summary of changes for this release Display information about ISPF PDF Terminate ISPF using log and list defaults to terminate ISPF Then select the DATASET option option 2 and press the Enter key OPTION gt 2 1 LIBRARY 2 DATASET 3 MOVE COPY 4 DSLIST 5 RESET 6 HARDCOPY 8 OUTLIST 9 COMMANDS 10 CONVERT 11 FORMAT 12 SUPERC 13 SUPERCE 14 SEARCH FOR D DATA MGMT Compress or print data set Print index listing Print rename delete or browse members Allocate rename delete catalog uncatalog or display information of an entire data set Move copy or promote members or data sets Print or display to process list of
248. or the command prompt the exec ends in error 11 14 05 390 V1R2 0 TSO E REXX User s Guide Protecting Elements in the Data Stack r Example of an Interactive Command Error EXECI PUSH prompti PUSH prompt2 CALL subl 7invellip EXIT SUB1 MAKEBUF ALLOCATE Even though the subroutine in the preceding example starts with the MAKEBUF command the stack elements will be used because MAKEBUF does not protect elements previously placed on the stack To protect elements on the data stack you can create a new data stack with the TSO E REXX NEWSTACK command Read the next section to see how the exec in the previous example can safely issue an interactive TSO E command To delete the new data stack and all elements in it use the TSO E REXX DELSTACK command Execs can create multiple stacks before deleting them Note Before an exec returns to its caller the called exec should issue a DELSTACK command for each NEWSTACK command it issued unless the called exec intends for the caller to also use the new data stack Creating a New Data Stack with the NEWSTACK Command The TSO E REXX NEWSTACK command creates a private data stack that is completely isolated from the original data stack The elements on the original data stack cannot be accessed by an exec or the routines that it calls until a DELSTACK command is issued When there are no more elements in the new data stack information is taken from the terminal Note
249. ords in the input string 5 6 OS 390 V1R2 0 TSO E REXX User s Guide Miscellaneous Functions Built In Functions Function Description ADDRESS Returns the name of the environment to which commands are currently being sent ARG Returns an argument string or information about the argument strings to a program or internal routine BITAND Returns a string composed of the two input strings logically ANDed together bit by bit BITOR Returns a string composed of the two input strings logically ORed together bit by bit BITXOR Returns a string composed of the two input strings eXclusive ORed together bit by bit CONDITION Returns the condition information such as name and status associated with the current trapped condition DATE Returns the date in the default format dd mon yyyy or in one of various optional formats ERRORTEXT Returns the error message associated with the specified error number EXTERNALS Returns the number of elements in the terminal input buffer In TSO E this function always returns a 0 LINESIZE Returns the current terminal line width minus 1 QUEUED Returns the number of lines remaining in the external data queue at the time when the function is invoked SOURCELINE Returns either the line number of the last line in the source file or the source line specified by a number TIME Returns the local time in the default 24 hour clock format hh mm ss
250. ormation about CPUs that X X are online SYSDSN returns information about the availability X of a data set e SYSVAR returns information about the user the X terminal the exec and the system Interaction with CLISTs Execs and CLISTs can call X each other and pass information back and forth For more information see Running an Exec from a CLIST on page 13 5 ISPF and ISPF PDF services An exec that is invoked X from ISPF can use that dialog manager s services Running Execs in a TSO E Address Space Earlier sections in this book described how to run an exec in TSO E explicitly and implicitly in the foreground When you run an exec in the foreground you do not have use of your terminal until the exec completes Another way to run an exec is in the background which allows you full use of your terminal while the exec runs Running an Exec in the Foreground Interactive execs and ones written that involve user applications are generally run in the foreground You can invoke an exec in the foreground in the following ways e Explicitly with the EXEC command For more information see Running an Exec Explicitly on page 2 11 e Implicitly by member name if the PDS containing the exec was previously allocated to SYSPROC or SYSEXEC Your installation might have a different name for the system file that contains execs For the purposes of this book it is called SYSEXEC For more information s
251. ormation you can specify with EXECIO DISKW For further information see TSO E REXX Reference SC28 1975 How to specify the number of lines to write To open a data set without writing records to it put a zero immediately following the EXECIO command and specify the OPEN operand EXECIO DISKW myoutdd OPEN Notes 1 To empty a data set issue this command to open the data set and position the file position pointer before the first record You then issue EXECIO 0 DISKW myoutdd FINIS to write an end of file mark and close the data set This deletes all records in data set MYOUTDD You can also empty a data set by issuing EXECIO with both the OPEN and FINIS operands 2 When you empty a data set the file to which the data set is allocated should not have a disposition of MOD If the file has a disposition of MOD opening and then closing the data set will not empty the data set To write a specific number of lines put the number immediately following the EXECIO command EXECIO 25 DISKW To write the entire data stack or until a null line is found put an asterisk immediately following the EXECIO command EXECIO DISKW When you specify the EXECIO command will continue to pull items off the data stack until it finds a null line If the stack becomes empty before a null line is found EXECIO will prompt the terminal for input until the user enters a null line Thus when you do not want to have terminal I O
252. ou to print output to a specified data set or a SYSOUT class In the input stream after the SYSTSIN DD you can issue TSO E commands and invoke execs and CLISTs The preceding example must be written in a fixed block 80 byte record data set To start the background job issue the SUBMIT command followed by the data set name for example REXX JCL SUBMIT rexx jcl For more information about running jobs in the background see TSO E User s Guide SC28 1968 Chapter 13 Using REXX in TSO E and Other MVS Address Spaces 13 7 Running Execs in a Non TSO E Address Space Running Execs in a Non TSO E Address Space Using an Exec Because execs that run in a non TSO E address space cannot be invoked by the TSO E EXEC command you must use other means to run them Ways to run execs outside of TSO E are e From a high level program using the IRXEXEC or IRXJCL processing routines From MVS batch with JCL that specifies IRXJCL in the EXEC statement TSO E provides the TSO E environment service IKJTSOEV Using IKJTSOEV you can create a TSO E environment in a non TSO E address space You can then run REXX execs in the environment and the execs can contain TSO E commands external functions and services that an exec running in a TSO E address space can use For information about the 7tsoes and how to run REXX execs within the environment see TSO E Programming Services SC28 1971 Processing Routine to Invoke an Exec from a Program To inv
253. out adding a space within the word broken This is an extended literal string that is broken in an awkward place Also note that the following two instructions are identical and yield the same result when displayed on the screen SAY This is a string is functionally identical to SAY This is a string These examples appear on the screen as This isa string In the first example the concatenation operator at the end of line 1 causes the deletion of any spaces when the two lines are concatenated for display In the second example the concatenation operator also concatenates the two strings without space when the line is displayed Ending an instruction The end of the line or a semicolon indicates the end of an instruction If you put more than one instruction on a line you must separate each instruction with a semicolon If you put one instruction on a line it is best to let the end of the line delineate the end of the instruction SAY Hi say Hi again say Hi for the last time This example appears on the screen as three lines Chapter 2 Writing and Running a REXX Exec 2 5 Syntax of REXX Instructions Hi Hi again Hi for the last time The following example demonstrates the free format of REXX r Example of Free Format RR kkk kk kkk kkk kkk kk kkkkkkk REXX eeeesetekekeedekekekekoekekejekdetekekekekdekejejekeeeiejee SAY This is a REXX literal string SAY This is a RE
254. p SYSPLEX SYSPLEX amp SYSSYMDEF SYMDEF Controlling Program Flow CLIST REXX Branching Branching IF THEN ELSE statements IF THEN ELSE instructions SELECT WHEN OTHERWISE END statements SELECT WHEN OTHERWISE END instructions Looping Looping Iterative DO Iterative DO DO WHILE END statements DO WHILE END instructions DO UNTIL END statements DO UNTIL END instructions Interrupting Interrupting END EXIT statements EXIT instruction GOTO statement SIGNAL instruction LEAVE instruction CALL instruction Calling another CLIST Calling another exec as an external subroutine EXEC command EXEC MYNEW CLIST CLIST1 VAR END PROC 1 VAR EXIT CALL instruction call execl var exit arg var return Calling a subprocedure Calling an internal subroutine Appendix C Comparisons Between CLIST and REXX C 3 CLIST REXX SYSCALL statement SYSCALL SOMESUB VAR END CALL instruction call subl var exit SOMESUB PROC 1 VAR subl arg var EXIT return Debugging CLIST REXX Debugging a CLIST Debugging an exec CONTROL SYMLIST LIST CONLIST MSG TRACE instruction trace i Interactive debug facility EXECUTIL TS and TRACE R Return codes for commands and statements Return codes for commands amp LASTCC amp MAXCC SET ECODE amp LASTCC RC ecode RC Trapping TSO E comman
255. page A 4 substitute the attributes from the appropriate system file in the following example If you are unsure about which system file is appropriate use the values from SYSEXEC Note In the ALLOCATE command specify a record format of VB as RECFM v b and a record format of FB as RECFM f b If your installation has no attribute recommendations and you have no attributes from the Preliminary Checklist you can use the attributes in the following example ALLOCATE DA rexx exec NEW DIR 10 SPACE 50 20 DSORG po RECFM v b LRECL 255 BLKSIZE 6120 For more information about the ALLOCATE command see TSO E REXX User s Guide SC28 1974 and TSO E Command Reference SC28 1969 2 Edit a member of the newly created PDS by selecting the ISPF PDF EDIT option option 2 and specifying the PDS name with a member name See the description for this step in the previous checklist on page A 7 Appendix A Allocating DataSets A 9 Checklist 3 Writing an Exec that Sets up Allocation to SYSEXEC 1 A 10 09 390 V1R2 0 TSO E Sample SETUP Exec Write an exec named SETUP that allocates data sets to SYSEXEC Create a data set member named SETUP in your exec PDS In SETUP issue an ALLOCATE command that concatenates your PDS to the beginning of all the data sets already allocated to SYSEXEC Include the data sets allocated to SYSEXEC from the list in the Preliminary Checklist on page A 3 If there
256. page 7 6 although you can also use a string separator within an argument template The following example passes three arguments separated by commas to an internal subroutine The first argument consists of two words String One that are parsed into three variable names The third variable name is set to null because there is no third word The second and third arguments are parsed entirely into variable names string2 and string3 CALL sub2 String One String Two String Three EXIT sub2 PARSE ARG wordl word2 word3 string2 string3 wordl contains String word2 contains One x word3 contains string2 contains String Two string3 contains String Three For more information about passing multiple arguments see TSO E REXX Reference SC28 1975 Exercise Practice with Parsing What are the results of the following parsing examples 1 quote Experience is the best teacher PARSE VAR quote wordl word2 word3 a word b word2 c word3 quote Experience is the best teacher PARSE VAR quote wordl word2 word3 word4 word5 word6 Chapter 7 Manipulating Data 7 9 Parsing Data PARSE VALUE Experience is the best teacher WITH wordl word2 word3 a word1 b word2 c word3 PARSE VALUE Experience is the best teacher WITH v1 5 v2 quote Experience is the best teacher PARSE VAR quote v1 v2 15 v3 3 v4 lt lt lt N l aooggw
257. pass information between REXX execs and other types of programs in a TSO E or non TSO E address space Because of the data stack s unique characteristics you can use the data stack specifically to Store a large number of data items for a single exec s use Pass a large number of arguments or an unknown number of arguments between a routine subroutine or function and the main exec Pass responses to an interactive command that can run after the exec ends Store data items from an input data set which were read by the EXECIO command For information about the EXECIO command see Using EXECIO to Process Information to and from Data Sets on page 12 2 Share information between an exec and any program running in MVS For more information about running REXX execs in MVS see Chapter 13 Using REXX in TSO E and Other MVS Address Spaces on page 13 1 Execute subcommands of a TSO E command issued from a REXX exec Passing Information Between a Routine and the Main Exec You can use the data stack to pass information from an exec to an external routine without using arguments The exec pushes or queues the information on the stack and the routine pulls it off and uses it as in the following example 11 6 05 390 V1R2 0 TSO E REXX User s Guide Using the Data Stack r Example of Using the Data Stack to Pass Information kkkkkkkkkkkkkkkkkkkkkkkkkkkkx REXX RRR RRR RRR RR KR KERR k kkk kk kk kkk kk This exec helps an inex
258. perienced user allocate a new PDS It prompts the user for the data set name and approximate size x and queues that information on the data stack Then it calls an external subroutine called newdata x RR kk RRR RRR kde kk k k k e kk de k k k kk k k k k kk e k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk message A data set name for a partitioned data set has three qualifiers separated by periods The first qualifier is usually a user ID The second qualifier is any name The third qualifier is the type of data set such as exec Generally the user ID is assumed so you might specify a data set name as MYREXX EXEC A new data set name cannot be the same as an existing data set name Please type a name for the new data set or type QUIT to end SAY What is the new data set name If you are unsure about SAY naming data sets type To end type QUIT PULL name DO WHILE name name QUIT IF name THEN DO SAY message PULL name END ELSE EXIT END SAY Approximately how many members will the data set have SAY 6 12 18 24 30 36 42 48 54 60 PULL number QUEUE name QUEUE number CALL newdata IF RESULT gt 0 THEN SAY An error prevented name from being allocated ELSE SAY Your data set name has been allocated Chapter 11 Storing Information in the Data Stack 11 7 Using the Data Stack r Example of the External Subroutin
259. plication has control When the application completes the original application level libraries are automatically reactivated Using ALTLIB with ISPF Under ISPF ALTLIB works the same as in line mode TSO E However if you use ALTLIB under line mode TSO E and start ISPF the alternative libraries you specified under line mode TSO E are unavailable until ISPF ends When you use ALTLIB under ISPF you can pass the alternative library definitions from application to application by using ISPEXEC SELECT with the PASSLIB operand for example ISPEXEC SELECT NEWAPPL ABC PASSLIB The PASSLIB operand passes the ALTLIB definitions to the invoked application When the invoked application completes and the invoking application regains control the ALTLIB definitions that were passed take effect again regardless of whether the invoked application changed them If you omit the PASSLIB operand ALTLIB definitions are not passed to the invoked application For more information about writing ISPF applications see OS 390 ISPF Services Guide SC28 1272 Examples of the ALTLIB Command In the following example an application issues the ALTLIB command to allow implicit execution of execs in the data set NEW EXEC to be searched ahead of SYSPROC ALTLIB ACTIVATE APPLICATION exec DATASET new exec The application could also allow searching for any private execs that the user has allocated to the file SYSUEXEC or SYSUPROC with the following comman
260. pported under the APPCMVS host command environment e ATBCUC1 Cleanup TP Unauthorized e ATBGTE2 Get Event e ATBPOR Post on Receipt e ATBQAQ2 Query Allocate Query e ATBRAL2 Receive Allocate ATBRFA2 Register for Allocate e ATBRJC2 Reject Conversation e ATBSAQ2 Set Allocate Queue Attributes e ATBSCA2 Set Conversation Accounting Information ATBSTE2 Set Event Notification e ATBTEA1 Accept Test e ATBTER 1 Register Test ATBTEU1 Unregister Test e ATBURA2 Unregister for Allocates e ATBVERS MVS Version Check ananasa 8 8 05 390 V1R2 0 TSO E REXX User s Guide Issuing Other Types of Commands from an Exec The following SAA CPI Communications calls are supported under the CPICOMM host command environment CMACCP Accept Conversation CMALLC Allocate e CMCFM Confirm e CMCFMD Confirmed CMDEAL Deallocate e CMECS Extract Conversation State e CMECT Extract Conversation Type e CMEMN Extract Mode Name e CMEPLN Extract Partner LU Name e CMESL Extract Sync Level e CMFLUS Flush e CMINIT Initialize Conversation CMPTR Prepare To Receive e CMRCV Receive e CMRTS Request To Send e CMSCT Set Conversation Type CMSDT Set Deallocate Type e CMSED Set Error Direction e CMSEND Send Data e CMSERR Send Error e CMSF Set Fill e CMSLD Set Log Data e CMSMN Set Mode Name e CMSPLN Set Partner LU Name e CMSPTR Set
261. pression within an instruction If so write a function The rest of this chapter describes how to write subroutines how to write functions and finally summarizes the differences and similarities between the two 6 2 09 390 V1R2 0 TSO E REXX User s Guide Writing a Subroutine Writing a Subroutine A subroutine is a series of instructions that an exec invokes to perform a specific task The instruction that invokes the subroutine is the CALL instruction The CALL instruction may be used several times in an exec to invoke the same subroutine When the subroutine ends it can return control to the instruction that directly follows the subroutine call The instruction that returns control is the RETURN instruction instruction s CALL subl gt instruction s EXIT sub1 instruction s RETURN __ Subroutines may be internal and designated by a label or external and designated by the data set member name that contains the subroutine The preceding example illustrates an internal subroutine named sub1 IMPORTANT NOTE Because internal subroutines generally appear after the main part of the exec when you have an internal subroutine it is important to end the main part of the exec with the EXIT instruction The following illustrates an external subroutine named sub2 REXX EXEC MAIN instruction s CALL sub2 instruction s Y REXX EXEC SUB2 instruction s
262. r 6 digits CPU ID x Using the SYSDSN Function The SYSDSN function determines if a specified data set is available for your use If the data set is available for your use it returns OK available SYSDSN myrexx exec available could be set to OK When a data set is not correct as specified or when a data set is not available the SYSDSN function returns one of the following messages e MEMBER SPECIFIED BUT DATASET IS NOT PARTITIONED e MEMBER NOT FOUND e DATASET NOT FOUND e ERROR PROCESSING REQUESTED DATASET e PROTECTED DATASET e VOLUME NOT ON SYSTEM e UNAVAILABLE DATASET e INVALID DATASET NAME data set name e MISSING DATASET NAME After a data set is available for use you may find it useful to get more detailed information For example if you later need to invoke a service that requires a specific data set organization then use the LISTDSI function For a description of the LISTDSI function see Using the LISTDSI Function on page 10 2 When you specify a fully qualified data set be sure to use two sets of quotation marks as follows one set to define a literal string to REXX and the other set to indicate a fully qualified data set to TSO E x SYSDSN proj5 rexx exec Or x SYSDSN proj5 rexx exec When you specify a data set that is not fully qualified and begins with your prefix usually your user ID you can use one set of quotation marks or none at all TSO E adds your prefix to
263. r implicit use of the EXEC command in the input stream Execs are invoked through the PARM parameter on the EXEC statement The first word on the PARM parameter is the member name of the PDS to be invoked Following words are arguments to be passed Information in the input stream is processed as TSO E commands and invocations of execs and CLISTs Information in the input stream is processed as input data for the exec that is running Output sent to a specified output data set or to a SYSOUT class Messages are displayed in the output file Output sent to a specified output data set or to a SYSOUT class Messages may appear in two places the JCL output listing and in the output file To suppress messages in the output file use the TRACE OFF instruction REQUIREMENTS TSO E BACKGROUND IKJEFT01 MVS BATCH IRXJCL The default DDs are SYSTSPRT and SYSTSIN The default DDs are SYSTSPRT and SYSTSIN Initiated by executing program IKJEFTO 1 Initiated by executing program IRXJCL JCL should be written in a fixed block 80 byte record data set JCL should be written in a fixed block 80 byte record data set Exec that is invoked can be either a member of a PDS or a sequential data set Exec that is invoked must be a member of a PDS Data set may be allocated to either SYSEXEC or SYSPROC Data set must be allocated to the SYSEXEC DD Chapter 13 Using REXX in T
264. r than the original line information that extends beyond the original number of bytes is truncated and EXECIO sends a return code of 1 If lines must be made longer write the data to a new data set When a changed line is shorter than the original line it is padded with blanks to attain the original line length 12 10 05 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information Updating a single line When updating a single line in a data set it is more efficient to locate the line in advance and specify the update to it rather than read all the lines in the data set to the stack locate and change the line and then write all the lines back For example you have a data set named DEPT5 EMPLOYEE LIST that contains a list of employee names user IDs and phone extensions Adams Joe JADAMS 5532 Crandall Amy AMY 5421 Devon David DAVIDD 5512 Garrison Donna DONNAG 5514 Leone Mary LEONE1 5530 Sebastian Isaac ISAAC 5488 To change a phone extension to 5500 on a particular line such as Amy Crandall s specify the line number in this case 2 and write the following instructions Notice the OLD attribute on the allocation The OLD attribute guarantees that no one else can use the data set while you are updating it r Updating a Specific Line in a Data Set ALLOC DA dept5 employee list F updatedd OLD EXECIO 1 DISKRU updatedd 2 LIFO PULL line PUSH Crandall Amy AMY 5500 EXECIO 1 DISKW update
265. ram development and for users when a program is run The benefits are Improved performance Reduced system load Protection for source code and programs Improved productivity and quality Portability of compiled programs Checking for compliance to SAA Chapter 1 Introduction 1 3 Benefits of Using a Compiler Improved Performance The performance improvements that you can expect when you run compiled REXX programs depend on the type of program A program that performs large numbers of arithmetic operations of default precision shows the greatest improvement A program that mainly enters commands to the host shows minimal improvement because REXX cannot decrease the time taken by the host to process the commands Reduced System Load Compiled REXX programs run faster than interpreted programs Because a program has to be compiled only once system load is reduced and response time is improved when the program is run frequently For example a REXX program that performs many arithmetic operations might take 12 seconds to run interpreted If the program is run 60 times it uses about 12 minutes of processor time The same program when compiled might run six times faster using only about 2 minutes of processor time Protection for Source Code and Programs Your REXX programs and algorithms are assets that you want to protect The Compiler produces object code which helps you protect these assets by discouraging people from
266. rands and combination of operands of the EXECIO command permit you to do many types of I O For example you can use the EXECIO command to Read information from a data set Write information to a data set Open a data set without reading or writing any records Empty a data set Copy information from one data set to another Copy information to and from a list of compound variables e Add information to the end of a sequential data set Update information in a data set one line at a time 12 2 09 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information Using the EXECIO Command EXECIO reads information from a data set with either the DISKR or DISKRU operands Using these operands you can also open a data set without reading its records Refer to Reading Information from a Data Set for more information about the DISKR and DISKRU operands EXECIO writes information to a data set with the DISKW operand Using this operand you can also open a data set without writing records or empty an existing data set Refer to Writing Information to a Data Set on page 12 6 for more information on the DISKW operand Before an exec can use the EXECIO command to read from or write to a data set the data set must meet the following requirements An I O data set must be e Either sequential or a single member of a PDS Previously allocated with the appropriate attributes for its specific purpose Some examples
267. rid myrexx exec A non fully qualified data set name can eliminate the prefix and is not enclosed within quotation marks myrexx exec If you use the EXEC command to explicitly invoke an exec the EXEC command processor requires a set of single quotation marks around the argument When passing a non fully qualified data set name as an argument you need not add additional quotation marks The following EXEC command is issued at the READY prompt and passes the data set name REXX INPUT as an argument to the exec contained in MYREXX EXEC TEST2 Both data sets are specified as non fully qualified data set names READY EXEC myrexx exec test2 rexx input exec When passing a fully qualified data set name as an argument with the EXEC command you must include more than one set of quotation marks one to indicate it is a fully qualified data set and one to indicate it is the argument to be passed Because TSO E commands process two sets of single quotation marks as one and do not recognize double quotation marks as does the language processor you must use three sets of single quotation marks The following EXEC command passes USERID REXX INPUT as an argument expressed as a fully qualified data set name READY EXEC myrexx exec test2 userid rexx input exec When passing a non fully qualified data set name as an argument while implicitly invoking the exec you need no quotation marks READY test2 rexx input To pass a fully qualified
268. ring after inserting one input string into another string after a specified character position LASTPOS Returns the starting character position of the last occurrence of one string in another LENGTH Returns the length of the input string OVERLAY Returns a string that is the target string overlaid by a second input string POS Returns the character position of one string in another REVERSE Returns a character string the characters of which are in reverse order swapped end for end STRIP Returns a character string after removing leading or trailing characters or both from the input string SUBSTR Returns a portion of the input string beginning at a specified character position SUBWORD Returns a portion of the input string starting at a specified word number TRANSLATE Returns a character string with each character of the input string translated to another character or unchanged VERIFY Returns a number indicating whether an input string is composed only of characters from another input string or returns the character position of the first unmatched character WORD Returns a word from an input string as indicated by a specified number WORDINDEX Returns the character position in an input string of the first character in the specified word WORDLENGTH Returns the length of a specified word in the input string WORDPOS Returns the word number of the first word of a specified phrase in the input string WORDS Returns the number of w
269. rnal function 6 11 internal subroutine 6 3 INTERPRET instruction 12 2 IRXEXEC 13 8 IRXJCL 13 8 ISPEXEC host command environment 8 6 ISREDIT host command environment 8 7 ITERATE instruction 4 12 J JCL job control language in MVS batch 13 8 in TSO background 13 7 K keyword instruction 2 7 L label instruction 2 8 language processor environment compared to host command environment 13 12 customizing 13 12 definition 13 12 IRXISPRM 13 12 X 6 08 390 V1R2 0 TSO E REXX User s Guide language processor environment continued IRXPARMS 13 12 IRXTSPRM 13 12 LEAVE instruction 4 12 4 18 library alternative ALTLIB B 1 application level B 1 exec A 1 system A 1 SYSEXEC 2 12 13 4 SYSPROC 2 12 13 4 system level B 1 user level B 1 LIFO last in first out 11 1 LINK host command environment 8 6 LINKMVS host command environment 8 6 LINKPGM host command environment 8 6 LISTALC STATUS command A 3 LISTDS command A 4 LISTDSI external function 10 2 literal string 2 3 logical Boolean operator false 0 3 10 true 1 3 10 type of 3 10 logical AND 3 10 logical NOT 3 10 loop altering the flow 4 12 combining types 4 17 conditional 4 14 DO FOREVER 4 11 DO UNTIL 4 16 DO WHILE 4 14 DO END 4 8 exiting prematurely 4 12 infinite 4 10 4 11 ITERATE 4 12 LEAVE 4 12 nested DO loop 4 18 repetitive 4 8 stopping 4 10 lowercase character changing to uppercase 2 15 2 18 preventing the change to uppercase 2 15 2 18 LU62 host comma
270. ronment 13 12 Customizing a Language Processor Environment 13 12 This chapter describes how to use REXX in TSO E and in non TSO E address spaces in MVS It also briefly describes the concept of a language processor environment Services Available to REXX Execs This book until now has described writing and running REXX execs in the TSO E address space Besides TSO E execs can run in other address spaces within MVS Where an exec can run is determined by the types of services the exec requires There are services that are available to an exec that runs in any address space TSO E or non TSO E and there are more specific services available only in a TSO E address space The following table lists all the services and where they are available function appears in Built In Functions on page 5 4 A longer description appears in TSO E REXX Reference SC28 1975 Service Non TSO E TSO E Address Address Space Space REXX language instructions These instructions are X X used throughout this book For a description of each one see TSO E REXX Reference SC28 1975 Built in functions A brief description of each built in X X Copyright IBM Corp 1988 1996 13 1 Services Available to REXX Execs Service Non TSO E TSO E Address Address Space Space TSO E REXX commands These commands consist of Data stack commands For more information see Chap
271. ruction 3 16 This chapter describes variables expressions and operators and explains how to use them in REXX execs One of the most powerful aspects of computer programming is the ability to process variable data to achieve a result The variable data could be as simple as two numbers the process could be subtraction and the result could be the answer answer numberl number2 Or the variable data could be input to a series of complex mathematical computations that result in a 3 dimensional animated figure Regardless of the complexity of a process the premise is the same When data is unknown or if it varies you substitute a symbol for the data much like the x and y in an algebraic equation x y 29 The symbol when its value can vary is called a variable A group of symbols or numbers that must be calculated to be resolved is called an expression Copyright IBM Corp 1988 1996 3 1 Using Variables Using Variables A variable is a character or group of characters that represents a value A variable can contain either single or double byte characters or a combination of single and double byte characters Double byte characters are valid only if you include OPTIONS ETMODE as the first instruction of your exec The following variable big represents the value one million or 1 000 000 big 1000000 Variables can refer to different values at different times If you assign a different
272. s on page 7 9 2 20 095 390 V1R2 0 TSO E REXX User s Guide Chapter 3 Using Variables and Expressions Using Variables 2 40 50 68 e ke ed ee web dope E rm 3 2 Varlable Names 4 sey wah ee Lee I ee np Al edd ts 3 2 Variable Values 2 to lll 3 3 Exercises Identifying Valid Variable Names 3 3 Using Expressions 2 les 3 4 Arithmetic Operators 2s 3 4 DIVISION aa BAAS Hoa ese Aad Sal Ue de om e EORR BAG 3 5 Order of Evaluation x uo RO SERERE ERE 3 5 Using Arithmetic Expressions 0 000000 0 3 6 Exercises Calculating Arithmetic Expressions 3 7 Comparison Operators ol 3 7 The Strictly Equal and Equal Operators 3 8 Using Comparison Expressions 2002000 3 8 Exercises Using Comparison Expressions 3 9 Logical Boolean Operators 20 0 000004 3 10 Using Logical Expressions 00002200005 3 10 Exercises Using Logical Expressions 3 11 Concatenation Operators 0 0 0 0 0 a 3 12 Using Concatenation Operators 3 12 Priority of Operators oen 3 12 Exercises Priority of Operators 20 4 3 14 Tracing Expressions with the TRACE Instruction 3 14 Tracing Operations 0 02002000000 00 3 14 Tracing Results 2 2 0 0 a a Ea a aa e aedy 3 15 Exercises Using the TRACE Inst
273. s please read the next two sections e Syntax of REXX Instructions e Running an Exec on page 2 10 Syntax of REXX Instructions Some programming languages have rigid rules about how and where characters are entered on each line For example CLIST statements must be entered in uppercase and assembler statements must begin in a particular column REXX on the other hand has simple syntax rules There is no restriction on how characters are entered and generally one line is an instruction regardless of where it begins or where it ends The Character Type of REXX Instructions You can enter a REXX instruction in lowercase uppercase or mixed case However alphabetic characters are changed to uppercase unless you enclose them in single or double quotation marks Using Quotation Marks in an Instruction A series of characters enclosed in matching quotation marks is called a literal string The following examples both contain literal strings SAY This is a REXX literal string Using single quotes SAY This is a REXX literal string Using double quotes You cannot enclose a literal string with one each of the two types of quotation marks The following is not a correct example of an enclosed literal string SAY This is a REXX literal string Using mismatched quotes When you omit the quotation marks from a SAY instruction as follows SAY This is a REXX string you see the statement in uppercase on your scr
274. s successful x DO SAY SAY newvar O records were written to all sample data END ELSE DO exec RC RC Save exec return code x SAY SAY Error during 1st EXECIO DISKW return code is RC SAY END D exec RC RC Save exec return code SAY SAY Error during 1st EXECIO DISKR return code is RC SAY D exec_RC 0 THEN If no errors so far continue DO RRR RRR RRR IK RRR k RRR AKER AK KKK KK RRA k KKK EA k k k RIKI k k k kk kkk kkk kkk At this time the stem variables newvar 0 through newvar 20 will contain residual data from the previous EXECIO We x issue the DROP newvar instruction to clear these residual values from the stem khoe kde I KERRI RRR AKER AK KKK AK KKK IK KKK EA KKK k kk k k k k kk k kkk kk kkk DROP newvar Set all stem variables to their uninitialized state x RRR RRR RR ERIK EERIE RAK REAR kk k k k k k IK KKK kk k k k k kk k k k k kk kkk kkk kkk Read all records from sample2 data and append them to the end of all sample data EK k k ek k e ke k eke k k k k ke k k e ke k k k k k k k kk k k k k k k k KKK kk k k k k kk k k k k kk kkk kkk kkk EXECIO DISKR myindd2 STEM newvar FINIS Read all records IF rc 0 THEN If read was successful DO E k e k ke e ek e e k k kk e k ke e ke k k ke k k kk k k k k KEI k k kk k k k k k k k k k k kk k k k k kk kkk At this point newvar O should be 10 indicating 10 records have be
275. ses by number x END average sum WORDS numlist Compute the average x RETURN average Chapter 6 Writing Subroutines and Functions 6 17 Summary of Subroutines and Functions Summary of Subroutines and Functions SUBROUTINES FUNCTIONS Invoked by using the CALL instruction followed by the subroutine name and optionally up to 20 arguments Invoked by specifying the function s name immediately followed by parentheses that optionally contain up to 20 arguments Can be internal or external Internal Can pass information by using common variables Can protect variables with the PROCEDURE instruction Can pass information by using arguments External Must pass information by using arguments Can use the ARG instruction or the ARG built in function to receive arguments Can be internal or external Internal Can pass information by using common variables Can protect variables with the PROCEDURE instruction Can pass information by using arguments External Must pass information by using arguments Can use the ARG instruction or the ARG built in function to receive arguments Uses the RETURN instruction to return to the caller Uses the RETURN instruction to return to the caller Might return a value to the caller Must return a value to the caller Returns a value by placing it into the REXX special variable RESULT Returns a value by repla
276. sname TRANSMIT dest DA dsname IF RC 0 THEN SAY Transmit successful ELSE SAY Return code from transmit was RC If the arguments passed to this exec were node1 mel and a sequential data set named new exec the interactively traced results would be as follows with each segment separated by a pause 8 x ARG dest dsname gt gt gt NODE1 MEL gt gt gt NEW EXEC gt gt uu Interactive trace TRACE OFF to end debug ENTER to continue 9 TRANSMIT dest DA dsname gt gt gt TRANSMIT NODE1 MEL DA NEW EXEC 0 message and 20 data records sent as 24 records to NODEI MEL Transmission occurred on 05 20 1989 at 14 40 11 10 IF RC 0 gt gt gt 1 n THEN 11 SAY Transmit successful gt gt gt Transmit successful Transmit successful EXECUTIL TS Command Another way to start interactive tracing is to issue the EXECUTIL TS trace start command or cause an attention interrupt and type TS The type of interactive tracing begun is equivalent to that of the TRACE R instruction except that tracing continues through all routines invoked unless it is specifically ended For information about ending interactive trace see Ending Interactive Trace on page 9 8 The EXECUTIL TS command can be issued from several environments it affects only the current exec and the execs it invokes Like other TSO E commands EXECUTIL TS can be issued from within
277. st second third fourth fifth 4 Weber Joe 91 ARG lastname firstname score 5 Baker Amanda Marie 95 PARSE ARG lastname firstname score 6 Callahan Eunice 88 62 PARSE ARG lastname firstname score ANSWERS 1 first 115 second 23 third 66 5 8 2 first 2 second 0 third 569 fourth 2E6 3 first 13 second 13 third 13 fourth 13 fifth null 2 18 0S 390 V1R2 0 TSO E REXX User s Guide Passing Information to an Exec 4 lastname WEBER firstname JOE score 91 5 lastname Baker firstname Amanda score Marie 95 6 lastname Callahan firstname Eunice score 88 Passing Arguments Values passed to an exec are usually called arguments Arguments can consist of one word or a string of words Words within an argument are separated by blanks The number of arguments passed depends on how the exec is invoked Passing Arguments Using the CALL Instruction or REXX Function Call When you invoke a REXX exec using either the CALL instruction or a REXX function call you can pass up to 20 arguments to an exec Each argument must be separated by a comma Passing Arguments Using the EXEC Command When you invoke a REXX exec either implicitly or explicitly using the EXEC command you can pass either one or no arguments to the exec Thus the ARG instruction in the preceding examples received only one argument One argument can consist of many words The argument if present will appear as a single string If yo
278. t host command environment for execs running in TSO E and ISPF is TSO Thus all commands are sent to TSO E for processing unless the exec changes the host command environment When an exec runs in an MVS environment TSO E command processors and services are not available to it For more information see Services Available to REXX Execs on page 13 1 In an MVS host command environment you can issue many of the TSO E REXX commands such as EXECIO MAKEBUF and NEWSTACK APPC MVS Host Command Environments The CPICOMM environment enables you to invoke the SAA CPI Communications calls and the LU62 and APPCMVS environments enable you to invoke APPC MVS calls You can write transaction programs in the REXX language using the LU62 CPICOMM or APPCMVS host command environments to issue APPC calls to a partner transaction program The CPICOMM host command environment allows transaction programs written in the REXX language to be ported across SAA environments The LU62 host command environment allows you to use specific features of MVS in conversations with transaction programs on other systems APPCMVS allows you to access APPC MVS callable services related to server facilities and for the testing of transaction programs Each of these host command environments enable REXX programs to communicate with other programs on the same MVS system different MVS systems or different operating systems in an SNA network The following APPC MVS calls are su
279. t name as argument 8 2 EXECUTIL HI 4 10 EXECUTIL SEARCHDD 13 4 EXECUTIL TE 9 8 EXECUTIL TS 9 4 9 5 issuing from an exec 8 2 LISTALC STATUS A 3 LISTDS A 4 prompting 8 4 10 7 overridden by item in the data stack 8 4 overridden by NOPROMPT in the PROFILE 8 4 SUBMIT 13 7 using parentheses 8 2 using quotation mark 8 2 using variable 8 3 with interactive prompt 8 4 10 7 11 16 TSO E environment service description 10 1 JCL example 13 7 running an exec 13 8 TSO E external function description 10 1 GETMSG 10 2 LISTDSI 10 2 MSG 10 4 MVSVAR 10 5 OUTTRAP 10 6 PROMPT 10 7 SETLANG 10 7 STORAGE 10 8 SYSCPUS 10 8 SYSDSN 10 9 X 10 os s90 V1R2 0 TSO E REXX User s Guide TSO E external function continued SYSVAR 10 10 TSO E REXX command DELSTACK 11 16 description 8 1 DROPBUF 11 10 EXECIO 12 3 EXECUTIL HI 4 10 EXECUTIL SEARCHDD 13 4 EXECUTIL TE 9 8 EXECUTIL TS 9 4 9 5 MAKEBUF 11 10 NEWSTACK 11 15 QBUF 11 11 QELEM 11 11 QSTACK 11 16 SUBCOM 8 11 U UNSDISP 10 12 UNSNUM 10 12 uppercase character changing from lowercase 2 15 2 18 preventing the change to 2 15 2 18 V variable compound 7 1 control 4 9 description 3 2 naming 3 2 RC See RC special variable representing a value in quotation marks 8 3 restriction on naming 3 2 RESULT See RESULT special variable shared variable in an internal function 6 12 shared variable in an internal subroutine 6 4 SIGL See SIGL special variable stem 7 2 type of value 3 3 use
280. t of HEADS If the user entered anything else the x subroutine tells the user that it is an invalid response and x The subroutine keeps repeating Information is returned to the main exec through commonly used variables RR kk RRR RRR REE R RRR RARER KARRI ERIK KEKE IA KIKI A KKK kk kkk k ER ERE DO UNTIL outcome correct SELECT WHEN response HEADS THEN outcome correct WHEN response TAILS THEN outcome correct WHEN response QUIT THEN EXIT OTHERWISE outcome incorrect SAY That s not a valid response SAY Heads tails or quit PULL response END END RETURN Try again IF compthrow r Possible Solution External Subroutine named THROW kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX KX FR k KKK RR KK REA kk kkk kkk k kkk kk This external subroutine receives the valid input from the user analyzes it gets a random throw from the computer and compares the two values If they are different the computer wins returned to the calling exec userthrow 0 ELSE userthrow 1 compthrow RANDOM 0 1 userthrow THEN outcome human ELSE outcome machine RETURN outcome If they are the same the user wins The outcome is then EK kk k k k e ek e e e e kek k k k e kk de ke k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kk k k kkk kk ARG input IF input HEA
281. t recently issued command Copyright IBM Corp 1988 1996 8 1 Issuing TSO E Commands from an Exec Issuing TSO E Commands from an Exec Like a CLIST a REXX exec can contain TSO E commands to be executed when the exec runs An exec can consist of nothing but TSO E commands such as an exec that sets up a user s terminal environment by allocating the appropriate libraries of data sets or the exec can contain commands intermixed with REXX language instructions Using Quotations Marks in Commands Generally to differentiate commands from other types of instructions enclose the command within single or double quotation marks When issuing TSO E commands in an exec it is recommended that you enclose them in double quotation marks If the command is not enclosed within quotation marks it will be processed as an expression and might end in error For example a word immediately followed by a left parenthesis is processed by the language processor as a function call Several TSO E commands one of which is ALLOCATE require keywords followed by parentheses ALLOC DA NEW DATA LIKE OLD DATA NEW If the ALLOCATE command in the example above was not enclosed in quotation marks the parentheses would indicate to the language processor that DA and LIKE were function calls and the command would end in an error Many TSO E commands use single quotation marks within the command For example the EXEC command encloses an argument within single
282. tem file Note Execs and CLISTs cannot access each other s variables and GLOBAL variables cannot be declared in a CLIST that is invoked from an exec The following examples demonstrate how a CLIST invokes an exec and how a number is returned to the invoking CLIST The CLIST named TEST explicitly executes an exec named EXEC1 EXEC1 calls EXEC2 which returns the result A OK EXEC1 then returns to the CLIST with a numeric return code of 100 if information was passed correctly and 50 if information was not passed correctly USERID MY CLIST TEST EXEC MYREXX EXEC EXEC1 EXEC WRITE THE RESULT FROM THE EXECS IS amp LASTCC END gt USERID MYREXX EXEC EXEC1 SAY We are now in Execl CALL Exec2 Y SAY The result from Exec2 is RESULT IF RESULT A OK THEN DO SAY The result is 1005 correct EXIT 100 END ELSE DO SAY The result is less than perfect EXIT 50 END 3 USERID MYREXX EXEC EXEC2 SAY Exec2 speaking var A OK RETURN var Chapter 13 Using REXX in TSO E and Other MVS Address Spaces 13 5 Running Execs in a TSO E Address Space The results from this series of programs is as follows We are now in Execl Exec2 speaking The result from Exec2 is A OK The result is 100 correct THE RESULT FROM THE EXECS IS 100 Sending a Return Code Back to the Calling CLIST As demonstrated in the previous example an e
283. ter 11 Storing Information in the Data Stack on page 11 1 DELSTACK X X DROPBUF X X MAKEBUF X X NEWSTACK X X QBUF X X QELEM X X QSTACK X X Other commands EXECIO controls I O processing X X EXECUTIL changes how an exec runs X Immediate commands HI from attention mode only X HE from attention mode only X HT from attention mode only X RT from attention mode only X TE X X TS X X SUBCOM queries the existence of a host X X command environment TSO E commands All TSO E commands both X authorized and unauthorized can be issued from an exec that runs in a TSO E address space For a description of these commands see TSO E Command Reference SC28 1969 TSO E External Functions GETMSG retrieves system messages issued X during an extended MCS console session LISTDSI returns data set attributes X MSG controls the display of messages for TSO E X commands e MVSVAR returns information about MVS TSO E X X and the current session 13 2 05 390 V1R2 0 TSO E REXX User s Guide Running Execs in a TSO E Address Space Service Non TSO E TSO E Address Address Space Space OUTTRAP traps lines of TSO E command output X PROMPT controls prompting for TSO E interactive X commands SETLANG controls the language in which REXX X X messages are displayed STORAGE retrieves and optionally changes the X X value in a storage address e SYSCPUS returns inf
284. ter 2 Writing and Running a REXX Exec Execs are easy to write and have few syntax rules Chapter 3 Using Variables and Expressions Variables expressions and operators are essential when writing execs that do arithmetic and comparisons Chapter 4 Controlling the Flow Within an Exec You can use instructions to branch loop or interrupt the flow of an exec e Chapter 5 Using Functions A function is a sequence of instructions that can perform a specific task and must return a value Chapter 6 Writing Subroutines and Functions You can write internal and external routines that are called by an exec Chapter 7 Manipulating Data Compound variables and parsing are two ways to manipulate data Note Although you can write a REXX exec to run in a non TSO E address space in MVS the chapters and examples in this part assume the exec will run in a TSO E address space If you want to write execs that run outside of a TSO E address space keep in mind the following exceptions to information in Part I e An exec that runs outside of TSO E cannot include TSO E commands unless you use the TSO E environment service see note In TSO E several REXX instructions either display information on the terminal or retrieve information that the user enters at the terminal In a non TSO E address space these instructions get information from the input stream and write information to the output stream SAY
285. ter the TRACE OFF instruction only during a pause while interactively tracing an exec End the Exec Interactive tracing automatically ends when the exec that initiated tracing ends You can cause the exec to end prematurely by entering the EXIT instruction during a pause The EXIT instruction causes the exec and interactive tracing both to end TRACE The question mark prefix before a TRACE option can end interactive tracing as well as begin it The question mark reverses the previous setting for interactive tracing While interactively tracing an exec you can also enter the TRACE instruction with any operand to discontinue the interactive debug facility but continue the type of tracing specified by the operand EXECUTIL TE The EXECUTIL TE Trace End command ends interactive tracing when issued from within an exec or when entered during a pause while interactively tracing an exec For more information about the EXECUTIL command see TSO E REXX Reference SC28 1975 9 8 05 390 V1R2 0 TSO E REXX User s Guide TSO E External Functions Chapter 10 Using TSO E External Functions TSO E External Functions 0 000002 2s 10 1 Using the GETMSG Function 00 0 000 000 10 2 Using the LISTDSI Function 0 10 2 Using the MSG Function oll llle 10 4 Using the MVSVAR Function llle 10 5 Using the OUTTRAP Function a 10 6 Using the PROMPT Function
286. ternal subroutine uses the RANDOM build in function to obtain a simulation of a throw of dice and compares the user input to the random outcome The main exec receives notification of who won the round Scores are maintained and displayed after each round computer 0 user 0 initialize scores to zero CALL check call internal subroutine check DO FOREVER CALL throw response call external subroutine throw IF RESULT machine THEN the computer won computer computer 1 increase the computer score ELSE the user won user user 1 increase the user score SAY Computer score computer Your score user SAY Heads tails or quit PULL response CALL check call internal subroutine check END EXIT E kk k k e e k e ke k k kek k k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk SAY This is a game of chance Type heads tails or quit SAY and press ENTER PULL response Chapter 6 Writing Subroutines and Functions 6 9 Writing a Subroutine check RR RRR RRR ER RRR ke de ke k k kk ee dee KEK AK kk k k k k kk k k k k kk k k k k kk k kk k kk k kk TAILS or QUIT asks the user to try again until the user enters valid input r Possible Solution Internal Subroutine named CHECK This internal subroutine checks for valid inpu
287. the COMMAND option of ISPF PDF Tain rat oso Mn dU D eS ARE TSO COMMAND PROCESSOR ENTER TSO COMMAND OR CLIST BELOW gt timegame ENTER SESSION MANAGER MODE gt NO YES or NO On the COMMAND line of any ISPF PDF panel as long as the member name is preceded by tso 2 12 09 390 V1R2 0 TSO E REXX User s Guide Interpreting Error Messages COMMAND gt tso timegame ISPF LIBRARY PROJECT gt PREFIX GROUP gt REXX gt gt gt TYPE gt EXEC MEMBER gt TIMEGAME Blank for member selection list ENTIAL DATA SET DATA SET NAME OTHER PARTITIONED OR SEQ VOLUME SERIAL BSS If not cataloged DATA SET PASSWORD gt If password protected PROFILE NAME gt Blank defaults to data set type INITIAL MACRO gt LOCK gt YES YES NO or NEVER FORMAT NAME gt MIXED MODE gt NO YES or NO To reduce the search time for an exec that is executed implicitly and to differentiate it from a TSO E command precede the member name with a READY timegame When a member name is preceded by TSO E searches a limited number of system files for the name thus reducing the search time Without the TSO E searches several files before it searches SYSEXEC and SYSPROC to ensure that the name you entered is not a TSO E command Exercises Running the Example Execs Create a PDS exec library using Checklist 1 or Checklist 2 in App
288. the data set name whether or not it is enclosed within a set of quotation marks x SYSDSN myrexx exec or x SYSDSN myrexx exec Chapter 10 Using TSO E External Functions 10 9 TSO E External Functions When you specify a variable that was previously set to a data set name do not enclose the variable in quotation marks Quotation marks would prevent the data set name from being substituted for the variable name variable myrexx exec x SYSDSN variable The following example uses the SYSDSN function together with the LISTDSI function to test whether a data set exists and whether it is a partitioned data set DO FOREVER SAY Enter a Data Set Name PARSE UPPER PULL dsname IF SYSDSN dsname OK THEN ITERATE FC LISTDSI dsname IF SYSDSORG PO THEN ITERATE SAY Okay dsname LEAVE END is SYSDSORG The SYSDSN function can be used only in REXX execs that run in the TSO E address space Using the SYSVAR Function The SYSVAR function retrieves information about MVS TSO E and the current session such as levels of software available your logon procedure and your user ID The information retrieved depends on the argument specified To retrieve the information use the SYSVAR function immediately followed by an argument value enclosed in parentheses For example to find out the name of the logon procedure of your current session use the SYSVAR function with the argument SYSPROC proc
289. ther useful built in functions to test input are WORDS VERIFY LENGTH and SIGN Exercise Writing an Exec with Built In Functions Write an exec that checks a data set member name for a length of 8 characters If a member name is longer than 8 characters the exec truncates it to 8 and sends the user a message indicating the shortened name Use the LENGTH and the SUBSTR built in functions as described in TSO E REXX Reference SC28 1975 ANSWER r Possible Solution kkkkkkkkkkkkkkkkkkkkkkkkkkkxk REX XK RRR RRR RRR KERR RRR RR RR RAR RRR kkk kk This exec tests the length of a name for a data set member If the name is longer than 8 characters the exec truncates the extra characters and sends the user a message indicating the x shortened member name RR RA RRR RR RRR ERK KERIKERI AK RIKER AKER AK KKK KKK IK k k k kk kkk k kk k kk SAY Please enter a member name PULL membername IF LENGTH membername gt 8 THEN Name is longer than 8 characters DO membername SUBSTR membername 1 8 Shorten the name to the first 8 characters SAY The member name you entered was too long SAY membername will be used END ELSE NOP 5 8 OS 390 V1R2 0 TSO E REXX User s Guide What are Subroutines and Functions Chapter 6 Writing Subroutines and Functions What are Subroutines and Functions 20 6 1 When to Write Subroutines vs Functions 6 2
290. tion SYSAPPCLU the APPC MVS logical unit LU name SYSDFP the level of MVS Data Facility Product MVS DFP SYSMVS the level of the base control program BCP component of OS 390 SYSNAME the name of the system your REXX exec is running on as specified in the SYSNAME statement in SYS1 PARMLIB member IEASYSxx SYSSECLAB the security label SECLABEL name of the TSO E session SYSSMFID identification of the system on which System Management Facilities SMF is active SYSSMS indicator whether DFSMS MVS is available to your REXX exec SYSCLONE MVS system symbol representing its system name SYSPLEX the MVS sysplex name as found in the COUPLExx or LOADxx member of SYS1 PARMLIB SYMDEF symbolic variables of your MVS system Chapter 10 Using TSO E External Functions 10 5 TSO E External Functions Using the OUTTRAP Function The OUTTRAP function puts lines of command output into a series of numbered variables each with the same prefix These variables save the command output and allow an exec to process the output Specify the variable name in parentheses following the function call SAY The OUTTRAP variable name is OUTTRAP var Displays the variable name in which command output is trapped In this example the variable var becomes the prefix for the numbered series of variables Vari var2 var3 and so on receive a line of output each If you do not set a limit to the number of output lines the numbering of variabl
291. to the single line that needs updating The data set remains open while you update the line and return the line with a corresponding EXECIO DISKW command EXECIO 1 DISKRU More about using DISKRU appears in Updating Information in a Data Set on page 12 10 How to access the data set An O data set must first be allocated to a ddname The ddname need not exist previously In fact it might be better to allocate it to a new ddname such as MYINDD in order not to interfere with previously established allocations You can allocate before the exec runs or you can allocate from within the exec with the ALLOCATE command as shown in the following example ALLOC DA io data F myindd SHR REUSE EXECIO DISKR myindd FINIS Option of specifying a starting line number f you want to start reading at other than the beginning of the data set specify the line number at which to begin For example to read all lines to the data stack starting at line 100 add the following line number operand EXECIO DISKR myindd 100 FINIS To read just 5 lines to the data stack starting at line 100 write the following EXECIO 5 DISKR myindd 100 FINIS To open a data set at line 100 without reading lines to the data stack write the following EXECIO DISKR myindd 100 OPEN 12 4 08 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information Options for DISKR and DISKRU Options you can use are OPEN To open a
292. truction 8 11 ALLOCATE command A 9 A 10 A 12 allocation description A 1 to a system file 2 12 13 4 A 1 to SYSEXEC A 10 to SYSPROC A 12 allocation checklist creating a data set with ALLOCATE A 9 creating and editing a data set using ISPF PDF A 5 preliminary A 3 writing an exec to allocate to SYSEXEC A 10 writing an exec to allocate to SYSPROC A 12 ALTLIB command B 1 using under ISPF B 2 APPC MVS services using examples APPC MVS calls 8 10 CPI Communications calls 8 10 ARG built in function 6 7 6 16 ARG instruction 2 17 6 6 6 15 7 4 Copyright IBM Corp 1988 1996 argument 2 19 ARG instruction 6 6 6 15 data set name 8 2 definition 2 19 in the EXEC command 8 2 passing to an exec 2 19 used to pass information to a function 6 15 used to pass information to a subroutine 6 6 arguments passing 2 19 using CALL instruction 2 19 using EXEC command 2 19 using REXX function call 2 19 arithmetic operator division type of 3 5 priority 3 6 type of 3 4 array See compound variable assignment instruction 2 7 ATTACH host command environment 8 6 ATTCHMVS host command environment 8 6 ATTCHPGM host command environment 8 6 background TSO JCL 13 7 running an exec 13 7 batch MVS JCL 13 8 running an exec 13 8 blank line 2 8 Boolean See logical operator built in function ADDRESS 8 11 ARG 6 7 comparison 5 5 conversion 5 5 DATATYPE 5 8 description 5 1 formatting 5 5 QUEUED 11 3 11 10 REXX language 5 4 arithmeti
293. ts in a function call it can specify only one expression on the RETURN instruction That expression can be a e Number RETURN 55 e One or more variables whose values are substituted or when no values were assigned return their names RETURN valuel value2 value3 Literal string RETURN Work complete Arithmetic comparison or logical expression whose value is substituted RETURN 5 number 6 16 0os 390 V1R2 0 TSO E REXX User s Guide Writing a Function Exercise Writing a Function Write a function named AVG that receives a list of numbers separated by blanks and computes their average as a decimal number The function is called as follows AVG numberl number2 number3 Use the WORDS and WORD built in functions For more information about these built in functions see TSO E REXX Reference SC28 1975 ANSWER m Possible Solution kkkkkkkkkkkkkkkkkkkkkkkkkkkkkk REX KX RRR RRR RRR kkk k kkk kk RRA kkk k ERE kk This function receives a list of numbers adds them computes their average and returns the average to the calling exec x EK kk k k e e ek REE RR RRR RIK KEK kk k k k k kk k k k KERIKERI KK KR IK KKK kk kkk k kkk kk ARG numlist receive the numbers in a single variable sum 0 initialize sum to zero DO n 1 TO WORDS numlist Repeat for as many times as there are numbers number WORD numlist n Word n goes to number sum sum number Sum increa
294. ty 41 Loop 6 Quantity 48 Loop 7 Quantity 56 Loop 8 You can substitute a DO UNTIL loop change the comparison operator from lt to gt and get the same results quantity 20 DO number 1 TO 10 UNTIL quantity gt 50 quantity quantity number SAY Quantity quantity END Loop number Nested DO Loops Like nested IF THEN ELSE instructions DO loops can also be within other DO loops A simple example follows DO outer 1 TO 2 DO inner 1 TO 2 SAY HIP END SAY HURRAH END The output from this example is HIP HIP HURRAH HIP HIP HURRAH If you need to leave a loop when a certain condition arises use the LEAVE instruction followed by the control variable of the loop If the LEAVE instruction is for the inner loop you leave the inner loop and go to the outer loop If the LEAVE instruction is for the outer loop you leave both loops To leave the inner loop in the preceding example add an IF THEN ELSE instruction that includes a LEAVE instruction after the IF instruction DO outer 1 TO 2 DO inner 1 TO 2 IF inner gt 1 THEN LEAVE inner ELSE SAY HIP END SAY HURRAH END 4 18 0S 390 V1R2 0 TSO E REXX User s Guide Using Looping Instructions The result is as follows HIP HURRAH HIP HURRAH Exercises Combining Loops 1 What happens when the following exec runs DO outer 1 TO 3 SAY Write a blank line DO inner 1 TO 3 SAY Outer outer
295. u plan to use commas within the argument string when invoking a REXX exec using the EXEC command special consideration must be given For example if you specify GETARG 1 2 or ex sam rexx exec getarg 1 2 the exec receives a single argument string consisting of 1 2 The exec could then use a PARSE ARG instruction to break the argument string into the comma separated values like the following PARSE ARG A B SAY A is A Will say A is 1 SAY B is B Will say B is 2 However because commas are treated as separator characters in TSO E you cannot pass an argument string that contains a leading comma using the implicit form of the EXEC command That is if you invoke the exec using GETARG 2 the exec is invoked with an argument string consisting of 2 The leading comma separator is removed before the exec receives control If you need to pass an argument string separated by commas and the leading argument is null that is contains a leading comma you must use the explicit form of the EXEC command For example ex sam rexx exec getarg 2 In this case the exec is invoked with an argument string consisting of 2 Chapter 2 Writing and Running a REXX Exec 2 19 Passing Information to an Exec For more information about functions and subroutines see Chapter 6 Writing Subroutines and Functions on page 6 1 For more information about arguments see Parsing Multiple Strings as Argument
296. urning a value from a subroutine A subroutine does not have to return a value but when it does it sends back the value with the RETURN instruction RETURN value The calling exec receives the value in the REXX special variable named RESULT SAY The answer is RESULT Returning a value from a function A function must return a value When the function is a REXX exec the value is returned with either the RETURN or EXIT instruction RETURN value The calling exec receives the value at the function call The value replaces the function call so that in the following example x value x function argumentl argument2 When to Write Subroutines vs Functions The actual instructions that make up a subroutine or a function can be identical It is the way you want to use them in an exec that turns them into either a subroutine or a function For example the built in function SUBSTR can be called as either a function or a subroutine As a function you invoke it as follows to shorten a word to its first eight characters x SUBSTR verylongword 1 8 x is set to verylong As a subroutine you would get the same results with the following instructions CALL SUBSTR verylongword 1 8 x is set to verylong x RESULT When deciding whether to write a subroutine or a function ask yourself the following questions e Is a returned value optional If so write a subroutine e Do need a value returned as an ex
297. ust to be safe enclose all commands in quotation marks As Input to an Exec When reading input from a terminal or when passing input from another exec the language processor also changes alphabetic characters to uppercase before they are processed To prevent translation to uppercase use the PARSE instruction For example the following exec reads input from the terminal screen and re displays the input as output r Example of Reading and Re displaying Input EK kk RRR EERE RRR kk k k k k kk k k RE REXX E E K k E AEk RRA RRR KK k kk k k k k Kk k k k k kk kkk This is an interactive REXX exec that asks a user for the name of an animal and then re displays the name EK kk k k e e ek e ke k e kek k k k e kk e k k k kk k k k k kk k k k k kk k k k k kk k k k k kk k k k k kk kkk k kkk kk SAY Please type in the name of an animal PULL animal Get the animal name SAY animal If you responded to the example with the word tyrannosaurus you would see on your screen TYRANNOSAURUS To cause the language processor to read input exactly as it is presented use the PARSE PULL instruction PARSE PULL animal Chapter 2 Writing and Running a REXX Exec 2 15 Passing Information to an Exec Then if you responded to the example with TyRannOsauRus you would see on the screen TyRannOsauRus Exercises Running and Modifying the Example Execs Write and run the preceding Example of Reading and Re displaying
298. utdd FINIS Close output file x FREE FI myinddl FREE FI myindd2 FREE FI myoutdd EXIT 0 Figure 12 9 EXECIO Example 6 continued 12 20 05 390 V1R2 0 TSO E REXX User s Guide Services Available to REXX Execs Chapter 13 Using REXX in TSO E and Other MVS Address Spaces Services Available to REXX Execs 020020005 13 1 Running Execs in a TSO E Address Space 13 3 Running an Exec in the Foreground 22 000 13 3 Things to Consider When Allocating to a System File SYSPROC or SYSEXEGO Lu nobel Ow Dri Ac a hd ete d Dt ae Sd 13 4 Allocating to SYSEXEC 2 2 200 2000022002 13 4 Allocating to SYSPROC 2 002000 05000504 13 4 Running an Exec from a CLIST 2 0 13 5 Sending a Return Code Back to the Calling CLIST 13 6 Running an Exec in the Background 2 04 13 7 Running Execs in a Non TSO E Address Space 13 8 Using an Exec Processing Routine to Invoke an Exec from a Program 13 8 Using IRXJCL to Run an Exec in MVS Batch 13 8 Using the Data Stack in TSO E Background and MVS Batch 13 10 Summary of TSO E Background and MVS Batch 13 11 CAPABILITIES Liei Rusa oM EAE tp Pee See a eS 13 11 REQUIREMENTS 2 2 2 2 2 s sss 13 11 Defining Language Processor Environments 13 12 What is a Language Processor Envi
299. value to big it gets the value of the new assignment until it is changed again big 999999999 Variables can also represent a value that is unknown when the exec is written In the following example the user s name is unknown so it is represented by the variable who SAY Hello What s your name PARSE PULL who Put the person s name in the variable who x Variable Names A variable name the part that represents the value is always on the left of the assignment statement and the value itself is on the right In the following example the word variable1 is the variable name variablel 5 SAY variablel As a result of the above assignment statement variablel is assigned the value 5 and you see on the terminal screen Variable names can consist of A Z uppercase alphabetic a Z lowercase alphabetic 0 9 numbers _ special characters X 41 X FE double byte character set DBCS characters ETMODE must be on for these characters to be valid in a variable name Restrictions on the variable name are The first character cannot be 0 through 9 or a period The variable name cannot exceed 250 bytes For names containing DBCS characters count each DBCS character as two bytes and count the shift out SO and shift in SI as one byte each e DBCS characters within a DBCS name must be delimited by SO X 0E and SI X OF Also note that 3 2 OS 390 V1R2 0 TSO E REXX User s Guide Usin
300. ve Exec Libraries with the ALTLIB Command B 1 Using the ALTLIB Command sss B 1 Stacking ALTLIB Requests aaa B 2 Using ALTLIB with ISPF 2 2 ee B 2 Examples of the ALTLIB Command B 2 Appendix C Comparisons Between CLIST and REXX C 1 Accessing System Information oll C 2 Controlling Program Flow aa C 3 Debugging 4 at dee dumis eae th bad ee e X ue C 4 Execution co Av at34 dob rolg eit tee bp ETE C 4 Vi OS 390 V1R2 0 TSO E REXX User s Guide Interactive Communication ss C 5 Passing Information oss sessi isosti snas deua ta mauta C 5 Performing File VO anaa aaa C 6 SYNTAX ese eee BE Suse eed ROW De do eed Puede aed C 7 Using Functions es C 7 Using Variables 2 0 2 20 00 2 a A aae aa a a e S C 7 INDEX Bae D A rs dealt cn B Ach ur P ins aed DBS hth DB oh s X 1 Contents Vii viii S 390 V1R2 0 TSO E REXX User s Guide Figures 10 1 12 1 12 2 12 3 12 4 12 5 12 6 12 7 12 8 12 9 Copyright IBM Corp 1988 1996 Language Codes for SETLANG Function That Replace the Function Gall 4 hate rera tona an ee ha hag tee atte Aledo th ANS ee Gh he 10 7 EXECIO Example 1 lens 12 13 EXECIO Example 2 2l sns 12 14 EXECIO Example3 sns 12 14 EXECIO Example 4 2 12 15 EXECIO Example 5 sn 12 16 EXECIO
301. ve right to use or distribute your comments in any way it believes appropriate without incurring any obligation to you Name Address Company or Organization Phone No Readers Comments We d Like to Hear from You Cut or Fold SC28 1974 00 Along Line Fold and Tape Please do not staple Fold and Tape PLACE POSTAGE STAMP HERE IBM Deutschland Entwicklung GmbH Department 3248 Sch naicher Str 220 D 71032 B blingen Federal Republic of Germany E Fold and Tape Please do not staple 1 FoldandTape Cut or Fold SC28 1974 00 Along Line File Number S370 390 39 Program Number 5645 001 on recycled paper containing 10 e Printed in the United States of America recovered post consumer fiber piace for OS390BCK PRNCV2 TET A
302. w how an expression is evaluated operation by operation x RR RAR RRR deje RIK KERIKERI A KERRI KEIR KKK AK KKK IKARIA KAR ERE RE A 1 B 2 C 3 D 4 TRACE I IF A gt B C lt 2 D THEN SAY At least one expression was true ELSE SAY Neither expression was true When this exec is run you see the following ps 12 IF A gt B C lt 2 D gt gt wj gt gt nou 20 og gt gt v3 gt L gt 2M gt gt waM gt 0 gt gu gt 0 gt mu gt 0 gt my THEN 13 SAY At least one expression was true gt L gt At least one expression was true At least one expression was true 3 16 05 390 V1R2 0 TSO E REXX User s Guide Chapter 4 Controlling the Flow Within an Exec Using Conditional Instructions 00 0000 00 eee eee 4 2 IF THEN ELSE Instructions 2020000000005 4 2 Nested IF THEN ELSE Instructions 20 4 3 Exercise Using the IF THEN ELSE Instruction 4 5 SELECT WHEN OTHERWISE END Instruction 4 6 Exercises Using the SELECT WHEN OTHERWISE END Instruction 4 7 Using Looping Instructions 2 200000 2 eee 4 8 Repetitive Loops ss ssp Rb rok Rom a ea le a Ae 4 8 Infinite Loops a a IR 4 10 DO FOREVER LOOPS s eR eR ance WE i 4 11 LEAVE Instruction los 4 12 ITERATE Instruction lll 4 12 Exercises Using Loops ll lll 4 13 Conditional Loops
303. was successful e MSG controls the display of TSO E messages The function returns the previous setting of MSG e MVSVAR uses specific argument values to return information about MVS TSO E and the current session OUTTRAP traps lines of TSO E command output into a specified series of variables The function call returns the variable name specified PROMPT sets the prompt option on or off for TSO E interactive commands The function returns the previous setting of prompt Copyright IBM Corp 1988 1996 10 1 TSO E External Functions SETLANG retrieves and optionally changes the language in which REXX messages are displayed The function returns the previous language setting e STORAGE retrieves and optionally changes the value in a storage address e SYSCPUS returns in a stem variable information about all CPUs that are online e SYSDSN returns OK if the specified data set exists otherwise it returns an appropriate error message e SYSVAR uses specific argument values to return information about the user terminal language exec system and console session Following are brief explanations about how to use the TSO E external functions For complete information see TSO E REXX Reference SC28 1975 Using the GETMSG Function The GETMSG function retrieves a system message issued during an extended MCS console session The retrieved message can be either a response to a command or any other system
304. xec can return a number to a CLIST with the EXIT instruction followed by the number or a variable representing the number The CLIST receives the number in the variable amp LASTCC When an exec invokes a CLIST the CLIST can return a number to the exec by the EXIT CODE statement with the number to be returned enclosed in parentheses after CODE The exec receives the number in the REXX special variable RC Note amp LASTCC is set after each CLIST statement or command executes as compared to RC which is set after each command executes To save the values of each special variable set a new variable with the value at the point where you want the special variable value saved In the following two examples exec USERID MYREXX EXEC TRANSFER passes an argument to CLIST USERID MY CLIST RECEIVE and the CLIST returns a number through the CODE parameter of the EXIT statement m USERID MYREXX EXEC TRANSFER RRR RRR REAR RRR RRR kk k k kk kk k k REXX KR KKK AKER K k k kk k k k K Kk K K k k kk kkk This exec passes a percent sign to a CLIST and depending on the success of the transfer the CLIST returns 100 if it was successful or 50 if it was not successful x RRR RRR RRA KR RRR RRR RRR RR k k k k k k k k kk k k k k k k k k k k kk k k k k kk k k k k kk k kkk kk kkk SAY We are about to execute CLIST RECEIVE and pass it EXEC my clist receive clist SAY We have returned from the CLIST IF RC 100 THEN
305. xec is finished RR kk RRR ke kk k ke k ee k k kk ee k e kk e dede kk k k k k kk k k k k kk k k k k kk k kk k kkk kk EXECIO 5 DISKR myindd 3 DO i 1 to5 PARSE PULL line stripline STRIP line t len LENGTH stripline IF len gt 20 THEN SAY Line stripline is long ELSE NOP END The file is still open for processing EXIT 0 Figure 12 3 EXECIO Example 3 12 14 05 390 V1R2 0 TSO E REXX User s Guide Using EXECIO to Process Information r EXECIO Example 4 RRRR RRR EERE REE RRRRERIERRERERK REX X RRR RR kk RRR kkk k KERR RR RARER kkk kk This exec reads first 100 records or until EOF of the data set allocated to INVNTORY Records are placed on data stack x in LIFO order If fewer than 100 records are read a message is issued K kk k k k e ek e e k k kek k k k e kk e ke k k kk k k k e kk e AKER AK k kk k k k k kk k k k k kk kkk k kkk kk eofflag 2 Return code to indicate end of file EXECIO 100 DISKR invntory LIFO return code RC IF return code eofflag THEN SAY Premature end of file ELSE SAY 100 Records read EXIT return code Figure 12 4 EXECIO Example 4 Chapter 12 Processing Data and Input Output Processing 12 15 Using EXECIO to Process Information r EXECIO Example 5 kkkkkkkkkkkkkkkkkkkkkkkkkkxkk REXX RR RR RRR RRR RR KR KERR RR RARER ERE kk This exec illustrates the use of EXECIO 0 to open empty
306. xecs 220020005 13 1 Running Execs in a TSO E Address Space 13 3 Running an Exec in the Foreground 22 000 13 3 Running an Exec in the Background llle 13 7 Running Execs in a Non TSO E Address Space 13 8 Using an Exec Processing Routine to Invoke an Exec from a Program 13 8 Using IRXJCL to Run an Exec in MVS Batch 13 8 Using the Data Stack in TSO E Background and MVS Batch 13 10 Summary of TSO E Background and MVS Batch 13 11 CAPABILITIES 2 Ja see ie d E ed dee ae Mates 13 11 REQUIREMENTS 2 2 2 2 2 2 ss 13 11 Defining Language Processor Environments 13 12 What is a Language Processor Environment 13 12 Customizing a Language Processor Environment 13 12 Part 3 Appendixes Appendix A Allocating Data Sets A 1 What is Allocation s 4008 emer week xeu y Baad ae Ges A 1 Where to Begin siteadi iom uae t Ie UIS A 2 Preliminary Checklist 22e A 3 Checklist 1 Creating and Editing a Data Set Using ISPF PDF A 5 Checklist 22 Creating a Data Set with the ALLOCATE Command A 9 Checklist 3 Writing an Exec that Sets up Allocation to SYSEXEC A 10 Checklist 4 Writing an Exec that Sets up Allocation to SYSPROC A 12 Appendix B Specifying Alternate Libraries with the ALTLIB Command B 1 Specifying Alternati
307. ype LOCK gt YES YES NO or NEVER MIXED MODE gt NO YES or NO Appendix A Allocating Data Sets A 7 In the edit session you can type REXX instructions such as the ones that follow C EDIT USERID REXX EXEC TIMEGAME COLUMNS 009 080 COMMAND gt SCROLL gt HALF Jokdekdek kkkkkkkkkkkkkkkkkkkkkkkk TOP OF DATA sesesee esee ke e eee eee ke eee 000001 xdxsdoeieieeeieek REXX AKER KERR RK EKER ERK KEKE RE RE 000002 This is an interactive REXX exec that compares the time 000003 from a user s watch with computer time x 000004 x xs e eee e ke e e e e e e e e e ke eee KIKI REIKI KAKA KA KEKE 000005 000006 SAY What time is it 000007 PULL usertime Put the user s response 000008 into a variable called 000009 usertime 000010 IF usertime THEN 000011 SAY O K Game s over 000012 ELSE 000013 DO 000014 SAY The computer says 000015 TSO system time command 000016 END 000017 000018 EXIT Jokdekdek kkkkkkkkkkkkkkkkkkkkkkk BOTTOM OF DATA k kkkkkkkkkkkkkkkkkkkkkkkkkkkk A 8 oS 390 V1R2 0 TSO E REXX User s Guide Checklist 2 Creating a Data Set with the ALLOCATE Command 1 Type an ALLOCATE command at the READY prompt to define the attributes of the new data set You can use the ALLOCATE command to create a PDS instead of using ISPF PDF panels If you noted attributes in the Preliminary Checklist on

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