DEFRAG options

You can use the following keywords to make more efficient use of the DEFRAG command:

DYNALLOC

Uses dynamic allocation to serialize the use of data sets, rather than enqueue. This method does not always provide cross-system serialization.

FRAGI(n)

Performs a DEFRAG operation only if the fragmentation index is more than n.

MAXMOVE(n,p)

Stops the DEFRAG run when n contiguous free tracks are assembled. If n contiguous free tracks already exist, DEFRAG processing attempts to further reduce the fragmentation of the volume, but no more than n tracks can be relocated. If more than n tracks must be relocated, DFSMSdss does not perform the DEFRAG request.

n: The number of free tracks that DFSMSdss is to try to assemble in a contiguous area.
p: The number of passes DFSMSdss is to make in attempt to assemble the tracks.

MAXTIME(nummins)

Stops the DEFRAG operation after the number of minutes specified has passed. This allows you to control the amount of time that the operation can run. MAXTIME is checked after each data set is prosessed. When the MAXTIME value is reached, the DEFRAG function ends.

nummins: Specifies number of minutes a DEFRAG operation can run.

MMOVPCT(n,p)

Stops the DEFRAG operation when n% contiguous tracks on the volume are assembled as free. If n% contiguous tracks already exist as free tracks, the DEFRAG function tries to further reduce the fragmentation of the volume but no more than n% tracks are relocated. If more than n% tracks must be relocated, no DEFRAG is performed.

n: The percentage of tracks on the volume that DFSMSdss is to try to assemble as free tracks in a contiguous area.
p: The number of passes DFSMSdss is to make in attempting to assemble the tracks.

PASSDelay

Specifies the time delay between the passes (p) specified in MAXMOVE(n,p) or MMOVPCT(n,p) to allow access to the volume between passes.

VERSION1

Specifies which version of DEFRAG is executed. During DEFRAG operations, you might want to execute the pre-z/OS V1R10 version of DFSMSdss DEFRAG. VERSION1 only supports volumes that are 65,520 cylinders or less. Any new function added to DEFRAG with z/OS® V1R10 or later is not available.

WAIT(s,r)

If the data set is unavailable, wait s seconds before retrying to obtain control of it and retry only r times.

To determine the fragmentation index of a volume without actually performing the DEFRAG operation, code the NORUN parameter on the EXEC statement in your JCL. In addition to the fragmentation index, the NORUN parameter lists the number of free cylinders, the number of free tracks, the number of free extents, the largest free extent size, and the percentage of free space on the volume. A map of the volume with the CCHH location of each data set or free space (in ascending order from cylinder 0, track 0) is also issued.