0x00851020 (8720416) An error occurred while accessing a shared memory object.

Explanation
A 64-Bit Virtual Storage Allocation macro failed
while trying to access a private memory object. The return and reason
codes for this error are displayed in the data fields in the server
log entry.

User response
To obtain a description of the error and determine
a corrective action, refer to the return and reason codes for the
macro IARV64 in the MVS Programming Assembler Services Reference.