Deciding to retry or percolate

Under certain circumstances (such as CANCEL), the system does not allow a retry. The SDWACLUP bit is on when the system prohibits a retry, and off when the system allows a retry.

If a recovery routine requests retry when it is not allowed, the system ignores the request and continues with percolation.

A recovery routine must determine whether it will attempt a retry. The determination might be very simple: if the SDWACLUP bit is on, retry is not even an option. But if retry is an option, the routine must make the decision based on the information it has gathered in the preceding steps.

By no means is a recovery routine required to attempt a retry, even when one is permitted. The recovery routine might decide not to retry if no SDWA is present, going on the assumption that serious problems probably exist. The routine might make the decision based on the particular completion code it finds in SDWACMPC, or based on information in the parameter area, or based on how successful the routine was in determining the cause of the error and fixing it. Perhaps the environment is so badly damaged that repair is beyond the scope of the recovery routine.

Once the decision is made, the recovery routine now does different things depending on whether it will retry or percolate.