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.
- 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.