IBM TSO/E REXX User Manual

The following two examples show the differing results when a function uses the
PROCEDURE instruction and when it doesn’t.
Example Using the PROCEDURE Instruction
/****************************** REXX *******************************/
/* This exec uses a PROCEDURE instruction to protect the variables */
/* within its function. */
/*******************************************************************/
number1 = 10
SAY pass() number2 /* Displays 7 NUMBER2 */
EXIT
pass: PROCEDURE
number1 = 7
number2 = 5
RETURN number1
Example Without the PROCEDURE Instruction
/******************************** REXX *****************************/
/* This exec does not use a PROCEDURE instruction to protect the */
/* variables within its function. */
/*******************************************************************/
number1 = 10
SAY pass() number2 /* displays 7 5 */
EXIT
pass:
number1 = 7
number2 = 5
RETURN number1
Exposing Variables with PROCEDURE EXPOSE: To protect all but specific
variables, use the EXPOSE option with the PROCEDURE instruction, followed by
the variables that are to remain exposed to the function.
Example Using PROCEDURE EXPOSE
/****************************** REXX *******************************/
/* This exec uses a PROCEDURE instruction with the EXPOSE option to*/
/* expose one variable, number1, in its function. */
/*******************************************************************/
number1 = 10
SAY pass() number1 /* displays 5 7 */
EXIT
pass: PROCEDURE EXPOSE number1
number1 = 7
number2 = 5
RETURN number2
For more information about the PROCEDURE instruction, see z/OS TSO/E REXX
Reference.
Passing Information by Using Arguments
A way to pass information to either internal or external functions is through
arguments. You can pass up to 20 arguments separated by commas in a function
call.
Writing a Function
Chapter 6. Writing Subroutines and Functions 81

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