These WLM enclaves are to facilitate zIIP processing. A ‘ziip-eligible’ SRB must be an enclave SRB.
The Packet Analyzer and Netmaster use ‘enclave SRBs’ which were created in the mid-90’s as part of MVS/ESA 5.2. These SRBs are like lightweight tasks, and have a priority scheme exactly the same as a task (TCB). They are preemptable, and cannot kill the system if they loop.
For Netmaster, we create an enclave (we need to do this so that we can ziip-enable it), and that enclave inherits the address space dispatching priority (as set by WLM etc). Thus, the enclave SRB gets exactly the same dispatching priority as the address space and/or existing task(s) (TCBs).
So in short, The zIIP processor allows certain existing z/OS workloads to execute on the zIIP processor. For these workloads to execute on the zIIP processor, they must execute as a Work Load Managed (WLM) Enclave SRB.