Modifying how JES2 performs initialization

The specific manner in which JES2 is initialized depends upon your choice of start options and initialization statements. You define how JES2 will perform initialization through the initialization options, which specify:
  • Whether JES2 is to warm start or cold start.
  • Whether JES2 should force the formatting of the spool volumes.
  • The ddname for the DD statement in the JES2 cataloged procedure that defines the input data set(s) for the initialization statements.
  • Whether JES2 should stop and give control to the operator for further statement input from the console after the parmlib input is exhausted.
  • Which data set, as defined by the CKPT1= or CKPT2= parameter on the CKPTDEF statement, should be used to access JES2 warm-start information.
  • Whether the checkpoint data set definitions should be reconfigured.
  • Whether JES2 will print a log of the initialization statements specified and any related diagnostics to the data set referenced by the HASPLIST DD statement in the JES2 cataloged procedure.
  • Whether JES2 will automatically start normal processing after initialization or wait for an operator command to start.
  • Which start options will be overridden (by specifying the OPTSDEF initialization statement).
You define which JES2 functions and device defaults are to be overridden by specifying the initialization statements:
  • Logical initiator characteristics
  • Internal reader characteristics
  • Local and remote device characteristics
  • Default job and SYSOUT class characteristics
  • NJE header and trailer buffers
  • Multi-access spool (MAS) control statements
  • Changes to certain JES2 default parameter values

You can control how JES2 schedules jobs by the way you specify these options and statements during JES2 initialization. Furthermore, you can respecify these options and statements to reflect changes in your system's configuration and workload any time JES2 is started.

Attention: Be aware, however, that some parameter changes require a JES2 cold start or all-member warm start and some parameters are ignored on a hot or warm start. These parameters are noted in the “Modification” heading for each parameter description in z/OS JES2 Initialization and Tuning Reference.

Carefully plan the initialization specification of each of these parameters to prevent having to revise them later through a warm start or cold start.