If you do not specify DATACLAS for a new data set and the storage administrator has provided an installation-written automatic class selection (ACS) routine, the ACS routine may select a data class for the data set. Check with your storage administrator to determine if an ACS routine will select a data class for the new data set, in which case you do not need to specify DATACLAS.

When RECORG is not specified, data sets associated with a data class, either by JCL or assigned by an ACS routine, will have DSORG defaulted to either physical sequential or a partitioned organization.