The SHMEM privilege lets the user's process
create global sections and mailboxes (permanent and temporary) in
memory shared by multiple processors if the process also has appropriate
PRMGBL, PRMMBX, SYSGBL, and TMPMBX privileges. Just as in local memory,
the space required for a temporary mailbox in multiport memory counts
against the buffered I/O byte count limit (BYTLM) of the process.
The privilege also lets a user's process
create or delete an event flag cluster in shared memory using the
Associate Common Event Flag Cluster ($ASCEFC) or the Disassociate
Common Event Flag Cluster ($DACEFC) system service.