Deleting SMS classes

You need to exercise caution when you delete storage, management and data classes, because a user or system might attempt to use a data set that references them.

For example, assume a data set has some specified migration attributes, and at some point it meets the migration criteria. After the data set has been migrated, you delete its associated management class. If the data set is recalled in the future, it must go through the management class ACS routine. If the ACS routine fails to override the undefined or deleted management class, the recall fails because a management class that does not exist is associated with the data set. If this occurs, you must either rewrite the management class ACS routine or specify that the data set should be recalled as a non-SMS data set. If you rewrite the ACS routine, you must check for the deleted management class and assign a valid management class to the data set. If you decide to bypass ACS processing, be aware that the data set is recalled to non-SMS storage.

Another consequence of deleting management classes involves DFSMShsm automatic processing. When DFSMShsm runs through its automatic cycle and processes data sets on the basis of their management class attributes, it attempts to retrieve nonexistent management class definitions. Consequently, DFSMShsm skips the processing of these data sets.

Instead of deleting storage classes and management classes, you should prevent any new allocation from using them by rewriting the corresponding ACS routine to override the deleted storage class or management class. It is safer and provides the possibility that all data sets that reference the management class or storage class might eventually be overridden. Also, you can identify all data sets with storage class or management class and then use ALTER to change to a new storage class or management class. If you decide to delete a storage class or management class, make certain that you inform all users well in advance.

Because data classes are used only at data set allocation, they do not have these problems. The original data class name is never referenced or reused.

If you decide to delete an SMS class, enter the following information on the pertinent Class Application Selection panel:

SCDS Name: 'SMS.SCDS1.SCDS'
xxxx CLASS NAME: *

Select option 1. After you press Enter, ISMF displays the Class List panel. Next to the SMS class that you want to delete, enter DELETE in the LINE OPERATOR column. When you press Enter, you see the Confirm Delete Request panel. Confirm that the displayed SMS class is the one that you want to delete. If it is, enter Y for yes and press Enter. The SMS Class List should appear with '*DELETE' in the LINE OPERATOR column next to the deleted SMS class.

After deleting SMS classes, activate the modified SMS configuration to make your changes part of the active configuration.