This configuration variable sets the number of temporary files used by SORT. The acceptable range is from 4 to 64. The default value is 8.
Increasing the number of files used will usually improve SORT performance, particularly for large sorts. Note that you must have enough available file handles to open all of the temporary files concurrently. In general, the number of files available is more important than the amount of memory used. If you are experiencing long sorts, try increasing the number of files before you increase the amount of sort memory.
The SORT verb removes all of its temporary files, except for one, prior to beginning its output phase.