Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (C)
Guardian Procedure Calls Reference Manual—522629-013
3-141
CONTROLMESSAGESYSTEM Procedure
operating system, reserving message-system control blocks is no longer
applicable, and the secondary functions of the procedure are accomplished by
calling CONTROLMESSAGESYSTEM. Although RESERVELCBS no longer
performs any function, it can still be called without error.