At the beginning of automatic primary space management in each of the DFSMShsm hosts, if SMS is active, DFSMShsm requests a list of all defined management classes and storage groups from SMS if the SMS configuration has changed since the last time DFSMShsm requested this information. If you have not provided any management class definitions, DFSMShsm builds a default management class definition. If SMS does not return any storage group definitions, DFSMShsm considers SMS to be inactive.
If SMS is active, DFSMShsm processes any SMS volumes that the z/OS® image is allowed to process and that have the AM=Y, AM=I, or AM=P attribute, and any non-SMS-managed primary volumes. If SMS is not installed and active, DFSMShsm processes only non-SMS-managed primary volumes. For purposes of the example, it is assumed that SMS is installed and active.
For more information about the exceptions to obtaining a new list of management classes, see DFSMShsm retrieval of management classes and storage groups.