Programming considerations

The following are programming considerations for Exit 8:

You can determine if Exit 8 is being invoked to process a transaction program by either:
- Determining if a $DSCT is contained in the $IOT
- Determining if byte JCTFLAG3 is set to JCT3TPI
If you need to alter information for a transaction program, you should make changes in the $DSCT rather than the $JCT. If you update the $JCT for a transaction program, the updates you make may not be applicable. You should consider implementing exit 31 if you will be updating the $DSCT for a transaction program.
Extending the JCT Control Block
If field X008CBID contains the 4-character string 'JCT ' (note the trailing blank), you can locate extensions to the job control table ($JCT) control block from this exit using the $JCTXGET macro. For more information about using this service, see z/OS JES2 Macros.