A21

Explanation
The system attempted to page-protect a storage
area. The segment table entry (SGTE) for this area was incorrect.
The error occurred in the modified link pack area (MLPA), the extended
pageable link pack area (PLPA), the fixed link pack area (FLPA), or
the extended FLPA.

System action
The system enters wait state X'A21'.
The system issues message IAR012W.

Operator response
If requested by the system programmer, obtain
a stand-alone dump.
If the error occurred in MLPA, EXTENDED
MLPA, BLDL, FLPA, or EXTENDED FLPA, attempt to reIPL the system without
this area. If the error occurred in MLPA or EXTENDED MLPA, try to
reIPL the system without the default page protection for this area.
Use the NOPROT option on the MLPA parameter.

System programmer response
Search the problem reporting databases
for a fix for the problem. If no fix exists, ask the operator to obtain
a stand-alone dump. Contact the IBM® Support
Center.  Provide the dump.

Source
Real storage manager (RSM)