IBM TSO/E REXX User Manual

When calling an external subroutine, CALL passes control to the exec name that is
specified after the CALL keyword. When the external subroutine completes, you can
use the RETURN instruction to return to where you left off in the calling exec.
For more information about calling subroutines, see “Chapter 6. Writing Subroutines
and Functions” on page 69.
SIGNAL Instruction
The SIGNAL instruction, like CALL, interrupts the normal flow of an exec and
causes control to pass to a specified label. The label to which control passes can
appear before or after the SIGNAL instruction. Unlike CALL, SIGNAL does not
return to a specific instruction to resume execution. When you use SIGNAL from
within a loop, the loop automatically ends; and when you use SIGNAL from an
internal routine, the internal routine will not return to its caller.
In the following example, if the expression is true, then the language processor
goes to the label Emergency: and skips all instructions in between.
instruction(s)
CALL sub1
instruction(s)
EXIT
sub1:
instruction(s)
RETURN
REXX.EXEC(MAIN)
instruction(s)
CALL sub2
instruction(s)
.
.
.
REXX.EXEC(SUB2)
instruction(s)
RETURN
Using Interrupt Instructions
58
z/OS V1R1.0 TSO/E REXX User’s Guide

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