When a job that uses GDG generations is restarted, all references to a GDG relative generation (e.g. +1, -3) will cause the
DD statement to reference the same physical file as the original job. The only time that this will not be true is where the
processing of the original job (or of other jobs that were run after the original job) has caused the GDG generation to be
rolled off, scratched, or deleted.
In the case of most mainframe jobs there will be no issues but you should be aware of the following scenarios:
- Where a job runs to successful (non-abend) completion and this results in a GDG generation being rolled off, that generation
will not be available on the restart, and any step that references the generation will fail with a
dataset not found message.
- Where a different job, which references the relevant GDGs and creates new relative generations, runs between the end of the
job in question and before the job restart takes place, it is possible that the generation referenced by the restarted job
will no longer be present.
- Where a job abends prior to completion, the abnormal termination disposition is applied as specified by the DISP= statements
in the JCL. In this scenario you will encounter problems if the step at which you restart references a generation that doesn't
exist as a result of the prior abnormal termination.