- Determine the addressing environment of the SRB, and specify it using the ENV parameter.
- Determine the priority at which you want to schedule the SRB.
There are two kinds of priorities: major and minor. The major priority is the dispatching priority. The dispatching priority is dynamically defined based on the goal defined in the service policy. A minor priority is equivalent to a task's dispatching priority. You can specify a minor priority for SRB routines so that they are dispatched before, with, or after tasks in the address space. You can assign a minor priority only to preemptable, client, or enclave priority SRBs.
The SRB may be scheduled for execution in any address space at any of the following major dispatching priorities:
- Client
- The priority of the address space named by the STOKEN. SRBs scheduled at this priority are preemptable. For more information about using SRBs with a client priority, see z/OS MVS Programming: Workload Management Services.
- Current
- The priority of the scheduling program's current home address space.
- Enclave
- The priority defined for the work running in the enclave. SRBs scheduled at this priority are preemptable.
- Global
- The priority of the highest priority work in the system.
- Local
- The priority of the address space into which the SRB is scheduled. The SRB is not preemptable, and its priority is higher than any preemptable work running in the address space.
- Preemptable
- The priority of the target home address space.
Preemptable SRBs may also be scheduled with a minor priority.
A minor priority of X'00' is the lowest and X'FF' is the highest. SRB routines with higher minor priority are dispatched before preemptable-class SRB routines with lower minor priority and before tasks in the same address space.
Use the FLAGS parameter of IEAMSCHD if you need to
differentiate between one or more of these cases that could result
from issuing IEAMSCHD:- SRB was definitely not queued for execution.
- SRB might have been queued for execution, but the system cannot know with certainty (this would be a very rare circumstance).
- SRB was definitely queued for execution.
- Issue IEAMSCHD with the appropriate parameters.