IBM Professional Series User Manual page 368

DIAGNOSE Code X'64' - Finding,
Loading, and Purging a Named Segment
Execution of DIAGNOSE Code X'64' controls the linkage
of discontiguous saved segments. Since VM/PC CP does
not support saved segments, the function return code to all
sub codes
will
be:
Return Code Meaning
44 Named segment does not exist
Appendix A. CP / CMS Interface A-29