The RELEASE option controls whether or not excess space on the SORTWK data sets will be released at the end of the input phase during JCL-initiated sorts where DISP=OLD is not specified on the SORTWK DD statement.
If RELEASE=ON is specified, MFX will release the space. This is the default. If RELEASE=OFF is specified, the excess space will not be released.
During a MAXSORT, excess space will be released only if SORTWK space exceeds the MAXWKSP value, and it will be released before the input phase begins.
Note that the RELSAMT option directly affects this option. If the RELSAMT default has not been changed, RELEASE=ON will not take effect unless at least 20 million bytes are sorted.