When a data set migrates for extent reduction, DFSMShsm immediately
requests a recall for that data set to the same volume. Under these
circumstances, DFSMShsm recalls the data set to the specified volume
with the same storage class, management class, and data class as were
in effect when the data set migrated. DFSMShsm does not invoke the
ACS routine for these data sets.
Note: DFSMShsm can be directed
to use the ACS routines for volume selection by using the Return-Priority
exit (ARCRPEXT). For more information about the ARCRPEXT exit, see
z/OS DFSMS Installation Exits.