Before jobs enter the system, the job entry subsystem (JES3) must be initialized to process work. Initialization of JES3 is the process of establishing control blocks used for JES3 processing. JES3 initialization takes place between the time that the START JES3 command is issued and the time that the processing of jobs begins.
Depending on the type of start the operator specifies, JES3 initialization is a three or four phase process. The phases are:
•Phase 1 determines the types of starts that are allowed for the main and ...