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SVC 055

SVC 055 is a Type 4 SVC issued by the End-Of-Volume (EOV) processing routine. This macro get a LOCAL lock and calls load module IGC0005E.

EOV processing is called when the end of a physical volume or current extent is reached. It allows a program to process multivolume sequential datasets.

For input datasets, an EOV is issued when the end-of-data has been reached on a volume and the next volume must be made ready for processing. For output datasets, an EOV is issued when the end of space on the volume or the current extent is reached and a new one is needed.

The EOV macro instruction identifies end-of-volume and end-of-dataset conditions. For an end-of-volume condition, EOV causes switching of volumes and verification or creation of standard labels. For an end-of-dataset condition, EOV causes your end-of-dataset routine to be entered.

Hints

If there is excessive wait time reported to SVC 055, check to see if a multivolume input file has only one drive assigned to it. If so, this means the job must wait for the tape to rewind and for the mounting of the next volume. Allocating another drive would help to eliminate the wait time for rewinding on one drive while mounting the next volume on another drive. Also check the block size of tape datasets. A larger block size could reduce the number of volumes needed for large datasets.

Reference Sources

IBM z/OS MVS Diagnosis Reference

IBM z/OS DFSMS Diagnosis Reference

IBM z/OS DFSMS Using Data Sets

IBM z/OS DFSMS Using Magnetic Tapes

IBM z/OS DFSMS Checkpoint/Restart