IBM TSO/E REXX User Manual

Chapter 1. Introduction
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
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. Using
REXX in TSO/E and Other MVS Address Spaces” on page 171.
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.
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
© Copyright IBM Corp. 1988, 2001 3

IBM TSO/E REXX Specifications

General

Brand	IBM
Model	TSO/E REXX
Category	Computer Hardware
Language	English

Summary

Part 1. Learning the REXX Language

Chapter 1. Introduction

Explains the REXX programming language, its features, and suitability for various users.

Chapter 2. Writing and Running a REXX Exec

Details the process of writing, running, and understanding REXX execs, including syntax rules and common issues.

Chapter 3. Using Variables and Expressions

Covers REXX variables, expressions, operators, and tracing techniques for data manipulation and calculations.

Chapter 4. Controlling the Flow Within an Exec

Explains how to alter REXX exec execution using conditional, looping, and interrupt instructions.

Chapter 5. Using Functions

Describes REXX functions, including built-in, user-written, and packages, and how to use them.

Chapter 6. Writing Subroutines and Functions

Guides on writing, calling, and passing information to REXX subroutines and functions.

Chapter 7. Manipulating Data

Covers REXX data manipulation using compound variables, stems, and various parsing techniques.

Part 2. Using REXX

Chapter 8. Entering Commands from an Exec

Explains how REXX execs can interact with the operating system by issuing TSO/E and host commands.

Chapter 9. Diagnosing Problems Within an Exec

Details techniques for diagnosing and debugging REXX execs using tracing and special variables.

Chapter 10. Using TSO/E External Functions

Describes TSO/E external functions available for interacting with the system and performing specific tasks.

Chapter 11. Storing Information in the Data Stack

Explains how to use the REXX data stack for temporary storage, passing information, and managing buffers.

Chapter 12. Processing Data and Input/Output Processing

Covers dynamic REXX expression modification and processing data to/from data sets using EXECIO.

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

Explains how to run REXX execs in TSO/E and non-TSO/E MVS address spaces and available services.

Part 3. Appendixes

Appendix A. Allocating Data Sets

Guides on creating and allocating data sets, including checklists for ISPF/PDF and ALLOCATE commands.

Appendix B. Specifying Alternate Libraries with the ALTLIB Command

Details using the ALTLIB command to specify and manage alternative libraries for implicit execution.

Appendix C. Comparisons Between CLIST and REXX

Compares REXX and CLIST languages, highlighting similarities and differences in features and capabilities.

Appendix D. Notices

Provides legal notices, warranty disclaimers, copyright, and trademark information.

Bibliography

TSO/E Publications

Lists IBM publications related to TSO/E, including administration, CLISTs, and general information.

Related Publications

Lists IBM publications related to z/OS MVS and ISPF, covering system programming and administration.

Index