Defining PARMLIB Start Parameters for the APPC/MVS Scheduler

The APPC/MVS transaction scheduler (ASCH) initiates and schedules TPs in response to inbound requests for conversations. Start parameter values in system PARMLIB member ASCHPMxx (for example, SYS1.PARMLIB(ASCHPMxx)) define and modify TP scheduling classes and other TP scheduling characteristics to ASCH.

ASCH is started by a system operator command. The operator command (can be part of initial program load) identifies the ASCHPMxx member (see Starting the APPC/MVS Transaction Scheduler). Both APPC/MVS (also started by operator command) and ASCH must be active before DFM LU 6.2 conversations can take place.

You can use an APPC/MVS CLASSADD definition to define the ASCH start parameters in ASCHPMxx, as shown in the following example. This example can be found in system SAMPLIB member GDEASCH (for example, SYS1.SAMPLIB(GDEASCH)) or in GDEASCH.

   CLASSADD CLASSNAME(A)
      MSGLIMIT(1000) MAX(10) MIN(1) RESPGOAL(1)

The parameters in this example do the following:

CLASSADD CLASSNAME(A): Defines a class of transaction initiators to ASCH. A transaction initiator is an entity, such as DFM, that functions as an APPC/MVS TP. TPs in the same class should have similar characteristics such as run-time, priority, schedule-type, and security.
The CLASSNAME parameter defines the class name as A. It must match the class name used in the TP profile for DFM.
MSGLIMIT(1000): Defines 1000 as the maximum number of messages in the message log data set for TPs in this class.
MAX(10): Defines 10 as the maximum number of transaction initiators allowed for this class.
MIN(1): Defines 1 as the number of transaction initiators in this class that will be started when ASCH is started.
RESPGOAL(1): Defines 1 second as the system response time goal for TPs running in this class.

For more information about defining ASCH and about scheduling TPs, see z/OS MVS Planning: APPC/MVS Management.