IBM TSO/E REXX Manuale utente

z/OS

TSO/E

REXX User’s Guide

SA22-7791-00



z/OS

TSO/E

REXX User’s Guide

SA22-7791-00



Note

Before using this information and the product it supports, be sure to read the general information under “Appendix D.

Notices” on page 205.

First Edition, March 2001

This edition applies to Version 1 Release 1 of z/OS (5694-A01) and to all subsequent releases and modifications

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Contents

Figures............................ix

Tables ............................xi

About This Book .......................xiii

Who Should Use This Book ....................xiii

How This Book Is Organized....................xiii

Terminology .........................xiii

Purpose of Each Chapter ....................xiv

Examples ..........................xiv

Exercises ..........................xiv

Where to Find More Information ..................xiv

Accessing Licensed Books on the Web ...............xiv

Using LookAt to Look Up Message Explanations ...........xv

Part 1. Learning the REXX Language......................1

Chapter 1. Introduction ......................3

What is REXX? .........................3

Features of REXX ........................3

Ease of use .........................3

Free format .........................3

Convenient built-in functions ...................4

Debugging capabilities .....................4

Interpreted language ......................4

Extensive parsing capabilities ...................4

Components of REXX.......................4

The SAA Solution ........................4

Benefits of Using a Compiler ....................5

Improved Performance .....................5

Reduced System Load .....................5

Protection for Source Code and Programs ..............6

Improved Productivity and Quality .................6

Portability of Compiled Programs..................6

SAA Compliance Checking ....................6

Chapter 2. Writing and Running a REXX Exec .............7

Before You Begin ........................7

What is a REXX Exec? ......................8

Syntax of REXX Instructions ....................9

The Character Type of REXX Instructions ..............9

The Format of REXX Instructions .................10

Types of REXX Instructions ...................12

Execs Using Double-Byte Character Set Names ............14

Running an Exec ........................16

Running an Exec Explicitly ...................16

Running an Exec Implicitly ...................17

Interpreting Error Messages ....................19

Preventing Translation to Uppercase .................20

From Within an Exec......................20

As Input to an Exec ......................20

Passing Information to an Exec ...................21

Using Terminal Interaction ....................21

Specifying Values when Invoking an Exec ..............22

Preventing Translation of Input to Uppercase .............23

Passing Arguments ......................24

Chapter 3. Using Variables and Expressions .............25

Using Variables.........................25

Variable Names .......................26

Variable Values ........................27

Exercises - Identifying Valid Variable Names .............27

Using Expressions .......................28

Arithmetic Operators ......................28

Comparison Operators .....................30

Logical (Boolean) Operators ...................32

Concatenation Operators ....................34

Priority of Operators ......................35

Tracing Expressions with the TRACE Instruction ............37

Tracing Operations ......................37

Tracing Results........................38

Chapter 4. Controlling the Flow Within an Exec............41

Using Conditional Instructions ...................42

IF/THEN/ELSE Instructions ...................42

Nested IF/THEN/ELSE Instructions ................43

SELECT/WHEN/OTHERWISE/END Instruction ............44

Using Looping Instructions ....................47

Repetitive Loops .......................47

Conditional Loops .......................52

Combining Types of Loops ...................55

Nested DO Loops .......................55

Using Interrupt Instructions ....................56

EXIT Instruction .......................57

CALL/RETURN Instructions ...................57

SIGNAL Instruction ......................58

Chapter 5. Using Functions ...................61

What is a Function? .......................61

Example of a Function .....................62

Built-In Functions ........................63

Arithmetic Functions ......................63

Comparison Functions .....................63

Conversion Functions .....................64

Formatting Functions......................64

String Manipulating Functions ..................64

Miscellaneous Functions ....................65

Testing Input with Built-In Functions ................66

Chapter 6. Writing Subroutines and Functions ............69

What are Subroutines and Functions? ................69

When to Write Subroutines vs. Functions ...............70

Writing a Subroutine .......................70

Passing Information to a Subroutine ................72

Receiving Information from a Subroutine ..............75

Writing a Function........................77

Passing Information to a Function .................79

Receiving Information from a Function ...............83

Summary of Subroutines and Functions................83

iv z/OS V1R1.0 TSO/E REXX User’s Guide

Chapter 7. Manipulating Data ...................85

Using Compound Variables and Stems ................85

What is a Compound Variable? ..................85

Using Stems .........................86

Parsing Data..........................87

Instructions that Parse .....................88

Ways of Parsing .......................89

Parsing Multiple Strings as Arguments ...............92

Part 2. Using REXX .............................95

Chapter 8. Entering Commands from an Exec ............97

Types of Commands .......................97

Issuing TSO/E Commands from an Exec ...............98

Using Quotations Marks in Commands ...............98

Using Variables in Commands ..................99

Causing Interactive Commands to Prompt the User ..........100

Invoking Another Exec as a Command...............100

Issuing Other Types of Commands from an Exec ............101

What is a Host Command Environment? ..............101

Changing the Host Command Environment .............106

Chapter 9. Diagnosing Problems Within an Exec ...........111

Debugging Execs .......................111

Tracing Commands with the TRACE Instruction ...........111

Using REXX Special Variables RC and SIGL ............112

Tracing with the Interactive Debug Facility .............113

Chapter 10. Using TSO/E External Functions ............119

TSO/E External Functions ....................119

Using the GETMSG Function ..................120

Using the LISTDSI Function ..................120

Using the MSG Function ....................122

Using the MVSVAR Function ..................123

Using the OUTTRAP Function ..................123

Using the PROMPT Function ..................124

Using the SETLANG Function ..................125

Using the STORAGE Function..................126

Using the SYSCPUS Function ..................126

Using the SYSDSN Function ..................126

Using the SYSVAR Function ..................127

Additional Examples ......................130

Function Packages .......................133

Search Order for Functions ...................134

Chapter 11. Storing Information in the Data Stack ..........135

What is a Data Stack? .....................135

Manipulating the Data Stack ...................136

Adding Elements to the Data Stack ................136

Removing Elements from the Stack ................137

Determining the Number of Elements on the Stack ..........137

Processing of the Data Stack ...................139

Using the Data Stack ......................140

Passing Information Between a Routine and the Main Exec .......140

Passing Information to Interactive Commands ............142

Issuing Subcommands of TSO/E Commands ............142

Contents v

Creating a Buffer on the Data Stack.................142

Creating a Buffer with the MAKEBUF Command ...........143

Dropping a Buffer with the DROPBUF Command ...........144

Finding the Number of Buffers with the QBUF Command ........144

Finding the Number of Elements In a Buffer.............145

Protecting Elements in the Data Stack ................147

Creating a New Data Stack with the NEWSTACK Command ......148

Deleting a Private Stack with the DELSTACK Command ........149

Finding the Number of Stacks ..................149

Chapter 12. Processing Data and Input/Output Processing .......153

Types of Processing ......................153

Dynamic Modification of a Single REXX Expression ...........153

Using the INTERPRET Instruction ................153

Using EXECIO to Process Information to and from Data Sets .......154

When to Use the EXECIO Command ...............154

Using the EXECIO Command ..................154

Return Codes from EXECIO ..................159

When to Use the EXECIO Command ...............159

Chapter 13. Using REXX in TSO/E and Other MVS Address Spaces ...171

Services Available to REXX Execs .................171

Running Execs in a TSO/E Address Space ..............173

Running an Exec in the Foreground................173

Running an Exec in the Background ...............176

Running Execs in a Non-TSO/E Address Space ............177

Using an Exec Processing Routine to Invoke an Exec from a Program 177

Using IRXJCL to Run an Exec in MVS Batch ............178

Using the Data Stack in TSO/E Background and MVS Batch ......180

Summary of TSO/E Background and MVS Batch ............180

CAPABILITIES .......................180

REQUIREMENTS ......................181

Defining Language Processor Environments .............181

What is a Language Processor Environment? ............181

Customizing a Language Processor Environment ...........182

Part 3. Appendixes .............................183

Appendix A. Allocating Data Sets .................185

What is Allocation? .......................185

Where to Begin ........................186

Preliminary Checklist ......................186

Checklist #1: Creating and Editing a Data Set Using ISPF/PDF ......187

Checklist #2: Creating a Data Set with the ALLOCATE Command......190

Checklist #3: Writing an Exec that Sets up Allocation to SYSEXEC .....191

Checklist #4: Writing an Exec that Sets up Allocation to SYSPROC .....192

Appendix B. Specifying Alternate Libraries with the ALTLIB Command 195

Specifying Alternative Exec Libraries with the ALTLIB Command ......195

Using the ALTLIB Command ..................195

Stacking ALTLIB Requests ...................196

Using ALTLIB with ISPF ....................196

Examples of the ALTLIB Command .................196

Appendix C. Comparisons Between CLIST and REXX .........197

Accessing System Information ...................198

vi z/OS V1R1.0 TSO/E REXX User’s Guide

Controlling Program Flow ....................199

Debugging ..........................200

Execution ..........................200

Interactive Communication ....................201

Passing Information.......................201

Performing File I/O .......................202

Syntax ...........................202

Using Functions ........................203

Using Variables ........................203

Appendix D. Notices ......................205

Programming Interface Information .................207

Trademarks..........................207

Bibliography .........................209

TSO/E Publications .......................209

Related Publications ......................209

Index ............................211

Contents vii

viii z/OS V1R1.0 TSO/E REXX User’s Guide

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