IBM TSO/E REXX User Manual

The SAA solution:
v 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.
v Defines common communications support that you can use to connect
applications, systems, networks, and devices.
v Defines a common user access that you can use to achieve consistency in
panel layout and user interaction techniques.
v 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:
v MVS
– TSO/E
– CICS
– IMS
v VM CMS
v Operating System/400 (OS/400)
v 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 program development and for users when a program is run.
The benefits are:
v Improved performance
v Reduced system load
v Protection for source code and programs
v Improved productivity and quality
v Portability of compiled programs
v Checking for compliance to SAA
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.
The SAA Solution
Chapter 1. Introduction 5

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