Using tapes with change accumulation

During the LOG INPUT phase, the maximum number of tape log files that R+/CHANGE ACCUM will allocate is the value of MAXLOGS or MAXDRIVES (whichever is less) minus the number of tape files allocated in the JCL for image copies if any are being created by a recovery.

If the MAXLOGS value or the MAXDRIVES value is zero, the number of tape log files is unlimited.

If fewer tape drives are available than specified by MAXDRIVES (as limited by MAXLOGS), the utility tries to complete log input by repeatedly waiting for a free tape drive. In this case, replying CANCEL to the WTOR for the tape unit causes the utility to wait before retrying the allocation. During this wait, the utility may complete processing of another tape log and free the tape drive so that the next attempt at allocation will succeed.

MAXDRIVES is also a consideration during the MERGE phase. A change accumulation run terminates with an error message if the total number of input and output change accumulation files on tape for any table space or partition exceeds MAXDRIVES (minus the number of tape files allocated in the JCL).