Abstract for TSO/E REXX User's Guide

Purpose of this information

This information 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 information

This information 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 programming experience, particularly in writing CLISTs for TSO/E. Because of the broad range of experience in readers, this information is divided into two parts.

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 z/OS TSO/E Primer. Experienced programmers new to REXX can also read this section to learn the basics of the REXX language.
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 information is organized

In addition to the two parts described in the preceding paragraphs, there are three appendixes at the end of the information.

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.
Specifying Alternate Libraries with the ALTLIB Command describes using the ALTLIB command.
Comparisons Between CLIST and REXX contains tables that compare the CLIST language with the REXX language.

Terminology

Throughout this information 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 information 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.

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 information, 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 DATASET(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.