You can either specify the DATACLAS keyword or have data characteristics assigned automatically.

External specification of DATACLAS

Users can specify the DATACLAS keyword to select a set of model data set characteristics for a new allocation. Users can override any model characteristics by specifying the appropriate JCL DD statement parameter. With the new space override attribute in Data Class, users can override the JCL DD statement SPACE related parameters with what is define in the Data Class. This override is all inclusive, which means, if override is ON, then the space parameters in Data Class will be use instead of the parameters specified in JCL.

Automatic assignment of data characteristics

Users can have data attributes assigned by your data class ACS routine.