Installation-Supplied ADRREBLK Exit Routine

The reblock installation exits routine gets control when a sequential or partitioned data set is being processed during a data set COPY or RESTORE if either:

You specify REBLOCK(dsn [...]) in the COPY or RESTORE statement, the options installation exits routine (ADRUIXIT) does not override it, and the data set being copied meets the filtering criteria passed in the REBLOCK sublist (fully- or partially-qualified data set names), or
The options installation exits routine forces all data set COPY or RESTORE functions to use the reblock installation exits routine.

Notes:

The reblock installation exits is not given control for RECFM=U data sets. However, PDS load module data sets are reblocked, if requested, by IEBCOPY COPYMOD.
The reblock installation exit will not be called when processing a zEDC format SAM data set.

The installation options exit routine cannot change the REBLOCK sublist (fully or partially qualified data set names), but:

It can prevent DFSMSdss from reblocking if you specified REBLOCK(dsn [...]).
It can force DFSMSdss to reblock all sequential or partitioned data sets being copied (equivalent to REBLOCK(**)).
If the reblockable indicator is on in the data set’s Format-1 DSCB (DS1REBLK), DFSMSdss automatically reblocks the data set to a system-determined block size. This indicator is on if the system determined a block size when the data set was created. The reblock installation exits routine is not called.

The reblock installation exits routine supplied with DFSMSdss passes a return code of zero, which allows DFSMSdss to select a block size.

You can replace the DFSMSdss-supplied exit routine to override the DFSMSdss-selected block size. If the exit routine passes an invalid block size, the data set is not processed and message ADR453E is issued.

The name of the reblock installation exits routine must be ADRREBLK.