You can insert both JES2 and MVS™ commands into your JES2 initialization data set. This is convenient, for example, to "automatically" start devices when JES2 initializes. For instance, operator commands can be used to start RJE lines during initialization. (RJE lines, unlike other devices, cannot be started automatically by an initialization statement.)Figure 1 contains a section called "Operator Commands" that shows a $S LINE command, a $T LINE command and a $VS command used to insert a MVS VARY command. IBM® suggests that you add as many such commands within your initialization date set as appropriate to your installation's needs. See JES2 operator commands and the $VS command in z/OS JES2 Commands.

During initialization, JES2 stores the operator commands in temporary message buffers. Then, when initialization is complete, JES2 processes the commands. To ensure that operator commands are completely processed before JES2 starts processing jobs, you should use the REQ start option, which lets the operator start JES2 processing. Alternatively, the $S command can be included as the last operator command in the initialization data set, eliminating the need for operator intervention.