IBM TSO/E REXX User Manual

To protect elements on the data stack, you can create a new data stack with the
TSO/E REXX NEWSTACK command. Read the next section to see how the exec in
the previous example can safely issue an interactive TSO/E command.
To delete the new data stack and all elements in it, use the TSO/E REXX
DELSTACK command. Execs can create multiple stacks before deleting them.
Note: Before an exec returns to its caller, the called exec should issue a
DELSTACK command for each NEWSTACK command it issued, unless the
called exec intends for the caller to also use the new data stack.
Creating a New Data Stack with the NEWSTACK Command
The TSO/E REXX NEWSTACK command creates a private data stack that is
completely isolated from the original data stack. The elements on the original data
stack cannot be accessed by an exec or the routines that it calls until a DELSTACK
command is issued. When there are no more elements in the new data stack,
information is taken from the terminal.
Note: When you issue the NEWSTACK, it is your responsibility to issue a
corresponding DELSTACK command.
All elements added to the data stack after the NEWSTACK command are placed in
the new data stack. The original stack contains the elements placed on the stack
before the NEWSTACK command.
Instructions that could be used to create the illustrated new stack are as follows:
PUSH 'oldA'
PUSH 'old1'
'NEWSTACK'
QUEUE 'newY'
PUSH 'newX'
In the Example of an Interactive Command Error, the MAKEBUF command did not
protect the elements in the stack. If you substitute the NEWSTACK command for
the MAKEBUF command, the elements become inaccessible.
Protecting Elements in the Data Stack
148
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