Using Compiled REXX Routines

REXX for CA JCLCheck and JCLNeat › Using Compiled REXX Routines

Using Compiled REXX Routines

CA JCLCheck provides an interface for REXX procedures with both the JCLCheck and JCLNeat components. REXX routines are often used in source form (not compiled) requiring the real time interpretation of each instruction as it is executed. If processing one job stream, this overhead is generally considered acceptable if it is even noticed at all. However, if processing a large number of job streams, this overhead can become excessive.

The following procedure describes the process that you can use to compile the REXX routines. This can provide a noticeable improvement by removing the overhead of interpreting each REXX instruction each time it is executed. The performance improvement will be limited by the amount of overhead resulting from the elimination of the interpretative process.

Procedure to compile REXX routines for JCLCheck or JCLNeat:

You must have licensed the IBM Compiler and Library for REXX. This will provide you with access to the REXX compiler.
Use the following JCL to perform the compile:
```
//REXXCOMP EXEC PGM=REXXCOMP,PARM='XREF'
//STEPLIB  DD  DSN=your.rexx.compiler.library,DISP=SHR
//SYSPRINT DD  SYSOUT=A
//SYSTERM  DD  SYSOUT=A
//SYSDUMP  DD  DUMMY
//SYSPUNCH DD  DUMMY
//SYSIN    DD  DSN=your.rexx.source.library(yourrexx),DISP=SHR
//SYSCEXEC DD  DSN=your.rexx.compiled.library(yourrexx),DISP=SHR
```
Notes:
- The use of the STEPLIB DD can be eliminated if the REXX compiler library is in the system LINKLIST.
- The use of the SYSIN DD is required to identify the source of input to the compiler.
- The use of the SYSCEXEC DD is required to identify the location in which the compiler will place the Compiled REXX routine.
  This is a PDS file with the following choice of DCB attributes:
  
  F or FB with LRECL greater than 20 and less than 32,760
  
  or
  
  V or VB with LRECL greater than 24 and less than 32,756
Modify the JCLCheck or JCLNeat JCL as follows:
Before:
```
//SYSEXEC DD  DSN=your.rexx.source.library,DISP=SHR
```
After:
```
//SYSEXEC DD  DSN=your.rexx.compiled.library,DISP=SHR
//        DD  DSN=your.rexx.source.library,DISP=SHR
```
Use the preceding for access to both Compiled and Non-Compiled routines. If a routine of the same name exists in both libraries, the compiled version of the routine will be selected for execution.

After:
```
//SYSEXEC DD  DSN=your.rexx.compiled.library,DISP=SHR
```
Use the preceding for access to only Compiled routines.

Additional information on the IBM REXX compiler can be found in the following manual: SAA REXX/370 User's Guide and Reference Release 1.3.