Specifying DISP=(NEW,DELETE) minimizes space loss problems. SMPWRK6 is generally needed only for the duration of the SMP/E job step. To keep the data set longer than that, you must use a different DISP value and compress the data set to reclaim space.
The SMS-related options DATACLAS, MGMTCLAS, STORCLAS, and DSNTYPE provide additional data set support. For more information, refer to z/OS DFSMS Using Data Sets.