OAM

For the OSREQ CHANGE command (&ACSENVIR='CHANGE'):

If storage class, or both storage class and management class, are specified, both the storage class and management class ACS routines are executed, in that order.
If only management class is specified, only the management class ACS routine is executed, with the old storage class used as input.

For the OSREQ STORE command (&ACSENVIR='STORE'):

If the object is the first object in a collection, the storage class, management class and storage group ACS routines are executed, in that order. These routines determine the defaults for the object collection.
Whenever storage class or management class is specified, the storage class and management class ACS routines are executed for the object with the specified classes as input. Then the ACS routines derive the initial storage class and management class for the object rather than having the object use the default initial storage and management classes for the collection.

At class transition time, as defined by the management class associated with an object, (&ACSENVIR='CTRANS'), the storage class routine and then the management class routine are executed.