When a job that uses GDG bias is restarted, all references to a GDG relative bias (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 Bias 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 Bias being rolled off, that Bias will not be available on the restart and any step which references that bias will fail with a "dataset not found" message.
- Where a different job, which references the relevant GDGs and creates new relative biases, runs between the end of the job in question and before the job restart takes place, it is possible that the bias 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 bias that doesn't exist as a result of the prior abnormal termination.
