Writing REXX checks

A REXX check consists of an exec containing one or more remote checks coded in REXX language instructions. This code is interpreted and executed by System REXX and runs in a System REXX address space, in an APF authorized environment defined by System REXX. You can identify your check as a REXX check by using the REXX(YES) parameter in the check definition.

Use the following documents for guidance on coding in the REXX language:

z/OS TSO/E REXX User's Guide
z/OS TSO/E REXX Reference
System REXX in z/OS MVS Programming: Authorized Assembler Services Guide

Look for REXX check information in our Redpaper™: There's lots of great experience-basecd information on writing REXX checks in Redpaper Exploiting the Health Checker for z/OS® infrastructure (REDP-4590-00).

In this chapter, we'll cover the following:

Sample REXX checks
REXX check basics
Using input data sets in a TSO-environment REXX check
Using REXXIN data sets
Using REXXOUT data sets
Defining a REXX check to IBM Health Checker for z/OS
Issuing messages from your REXX check with the HZSLFMSG function
Writing a check with dynamic severity levels
Controlling check exception message WTOs and their automation consequences
The well-behaved REXX check - recommendations and recovery considerations
Debugging REXX checks