The cause of the DYL-901E error baffles many customers:
ERROR DYL-901E KEYWORD OF xxxxxxxx IS NOT USED IN YOUR SYSTEM
where xxxxxxxx is ACCEPT, CASE, DOUNTIL, DOWHILE, GOTO, PERFORM, REJECT, or WHEN
VISION:Results provides various programming modes you can use depending upon your requirements. Once the mode has been selected, it remains in effect for all report requests in a multiple report run unless it is changed. CONVENTIONAL is the default mode and sets the mode to standard VISION:Results.
STRUCTURED mode allows the use of structured features in VISION:Results such as PERFORM. To adhere to strict structured constructs, this mode disables the usage of the GOTO, ACCEPT, and REJECT commands.
STRUCTURED2 mode allows all structured features, as well as the GOTO, ACCEPT, and REJECT commands, establishing a less restrictive environment than OPTION STRUCTURED.
For more information see VISION:Results for z/OS release 6 documentation:
Reference Guide, Chapter 8: Structured Programming
Getting Started, Chapter 6: Structured and USERDEFAULT Mode Programming
To resolve the error at the application level, OPTION STRUCTURED or OPTION STRUCTURED2 is needed to establish the appropriate mode.
The mode can be established at the site level via the DYLINSTL macro PROGMOD parameter.
If the job has previously executed successfully, check the parameter values on the Default Options display page to verify they match the last successful execution. If the release changed they will probably need to be matched. If maintenance has been applied, check the loadlibs affected in the SMP/E steps so see if the DYLPCPS module was overlaid and the CUSTMJCL job needs to be re-executed.