When using the RECALL/RECOVER command, if you want to RECALL a data set, then the data set already exists. If you want to RECOVER a data set, then either the data set exists or has been deleted. The data set is recovered by restoring data from a DFSMShsm backup copy to the target data set.
The data class ACS routine is not invoked, because either the data set already exists, or the characteristics of the data set are derived from the backup copy.
The storage class ACS routine is invoked to determine whether the data set is system-managed. The restored data might come from a non-system-managed backup copy, and is allocated as system-managed or non-system-managed as determined by the ACS routines.
The management class ACS and storage group ACS routines are invoked only if the data set is system-managed.
Before recalling a data set, DFSMShsm checks if a class transition was missed while that data set was migrated. If a class transition was missed, then DFSMShsm runs the ACS routines with ACS environment SPMGCLTR to determine any new SMS construct names. Using the newly retrieved management class name, DFSMShsm repeats the check to see if a class transition was missed, until the appropriate management and storage classes and storage groups are found. These new management class, storage class, and storage groups are then used for the RECALL.