Blockset sorting performance can be improved by using memory object sorting.

The MOSIZE parameter sets the maximum amount of memory object storage to be used during a run. Specifying MOSIZE=MAX allows DFSORT to optimize the maximum size of a memory object to be used during a run, subject to other system and concurrent Hipersorting, memory object sorting and dataspace sorting activity throughout the run. Total memory object sorting activity on a system can be further limited by the EXPMAX, EXPOLD, and EXPRES installation options. See the description of MOSIZE in OPTION control statement for more information.