SCHDOFLZ parameter
Threshold for activating zIIP subtasks
Summary
- Default value
- 2
- Parameter type
- System
- Where set
- On User 0's parameter line or reset by system manager.
- Related products
- All
- Introduced
- Model 204 V7.4
Description
Applies to z/OS only
On a z/OS system, Model 204 zIIP support enables you to offload Model 204 work from regular processors to zIIP processors.
SCHDOFLZ specifies the target number of threads on the zIIP offload queue per active task. Setting this parameter makes the Model 204 zIIP subtask scheduler more responsive to instantaneous increases in load.
The default value of 2 means that if there are more than twice as many units of zIIP offloadable work waiting to be processed in a zIIP subtask as there are active subtasks, and fewer than AMPSUBZ subtasks are currently running, another zIIP offload subtask is activated.
SCHDOFLZ has no effect if zIIP SRBs are not in effect in an Online (NMPSUBZ=0) or if the number of active SRBs (AMPSUBZ) is set to 0 or 1. (If AMPSUBZ=1, a zIIP subtask is activated as soon as there is any offloadable work and then runs until there is no more offloadable work for it to process.)
The SCHDOFL parameter performs the same function as SCHDOFLZ for non-SRB MP subtasks and the SCHDOFLS parameter controls how aggressively MP subtasks will be started to help zIIP subtasks out and how aggressively MP subtasks will take work from zIIP subtasks.