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CHAP — Change dispatching priority z/OS MVS Programming: Assembler Services Reference ABE-HSP SA23-1369-00 |
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DescriptionCHAP changes the dispatching priority of the task or any of its
subtasks relative to the other tasks in the address space. It does
not change the priority relative to other tasks in the system. CHAP
may also change the limit priority of a subtask. (See the topic “Priorities”
in the z/OS MVS Programming: Assembler Services Guide.)
The algebraic sum of the priority value and the dispatching priority
of the subject task determine the new dispatching priority.
EnvironmentThe requirements for the caller are:
Programming requirementsNone. RestrictionsNone. Input register informationBefore issuing the CHAP macro, the caller does not have to place any information into any register unless using it in register notation for a particular parameter or using it as a base register. Output register informationWhen control returns to the caller, the GPRs contain:
When control returns to the caller, the ARs contain:
Performance implicationsNone. SyntaxThe CHAP macro is written as follows:
ParametersThe parameters are explained as follows:
ABEND codes07F See z/OS MVS System Codes for an explanation and programmer responses for these codes. Return and reason codesNone. Example 1Lower the dispatching priority of the subtask TCB by two. The subtask
TCB's address is in a fullword which register 1 addresses. The subtask
TCB will be repositioned on the dispatching queue in accordance with
its new dispatching priority.
Example 2Reposition the TCB of the task issuing CHAP at the bottom of the
group of TCBs on the dispatching queue for the address space, having
the same dispatching priority as that task.
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Copyright IBM Corporation 1990, 2014
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