USAGE NOTES

The caller is assumed to have addressability to the TVT using register 12 and to the caller's FCT using register 11.
If a DSP currently owns a lock obtained with this service and requests a second lock, the DSP is failed by the lock service routine. The FAILDSP issued in the lock service routine has a dump code of DM054. Before the FAILDSP is issued, the caller's registers are restored from FCTWKSAV and the caller's return address is loaded into register 2, so that it will not be destroyed by the FAILDSP call.
A DSP should not wait while holding a JES3 lock because this could keep other FCTs from using the locked resource, and could result in a deadlock.