Data Class

A data class is a collection of allocation and space attributes that the system uses when creating a data set. If SMS is active, a data class can be assigned to any data set. For non-SMS-managed DASD data sets, the system uses the allocation attribute values of the data class, but it does not save the data class name. If you alter a data class definition, SMS applies the changes to all new data sets and certain existing data sets that use the data class.

For example, you can specify the record organization and space allocation values for a data set. You can specify compaction for tape data sets to make more efficient use of your tape cartridges. Table 1 shows the types of data set attributes that you can associate with a data class.

Table 1. Types of data class attributes
Record, key, and space attributes Volume attributes Data set attributes VSAM attributes Backup-while-open attributes Tape media attributes compaction media type recording technology performance scaling

Related reading: For more information about defining data classes, see the z/OS DFSMSdfp Storage Administration.