Description

The STATUS macro with the START or STOP option starts or stops a unit or units of work. The STATUS macro with the SET or RESET option places a program in process-must-complete mode or ends process-must-complete mode. Process-must-complete mode postpones delays from the following:
  • Asynchronous exits
  • Asynchronous abends (CALLRTM TYPE=ABTERM for tasks or CALLRTM TYPE=SRBTERM for preemptable SRBs)
  • Status stops (by issuing the STATUS macro with the STOP option)
  • Timer exits
  • Dumping
  • Swapping
  • Attention exits

Process-must-complete mode prevents a CANCEL command from stopping a program already running but it does not postpone external interrupts or interrupts from I/O.

The description of the STATUS macro has two parts: the START/STOP option and the SET/RESET option. z/OS MVS Programming: Assembler Services Reference IAR-XCT describes the STATUS macro START and STOP options with the exception of the SRB and ASID parameters. These parameters, which are available only to supervisor state and key 0 callers, allow the caller to manipulate the dispatchability status or SRBs.

See z/OS MVS Programming: Authorized Assembler Services Guide for more information on how to use the STATUS macro SET and RESET options and z/OS MVS Programming: Assembler Services Guide for more information on how to use the STATUS macro START and STOP options.

Parent topic: STATUS — Control dispatchability or process-must-complete state

Environment

The requirements for the caller issuing STATUS with the START or STOP parameters are:

Environmental factor Requirement
Minimum authorization: Problem state or supervisor state, with any PSW key. For SRB and ASID parameters, supervisor state and PSW key 0.
Dispatchable unit mode: Task
Cross memory mode: PASN=HASN=SASN or PASN¬=HASN¬=SASN
AMODE: 31-bit
ASC mode: Primary or access register (AR)
Interrupt status: Enabled or disabled for I/O and external interrupts
Locks: No locks held
Control parameters: No requirements

The requirements for the caller issuing STATUS with the SET or RESET parameters are:

Environmental factor Requirement
Minimum authorization: Supervisor state, with PSW key 0.
Dispatchable unit mode: Task or preemptable SRB.
Cross memory mode: PASN=HASN=SASN or PASN¬=HASN¬=SASN
AMODE: 31-bit
ASC mode:
  • For task mode: Primary or access register (AR).
  • For SRB mode: Primary.
Interrupt status: Enabled or disabled for I/O and external interrupts
Locks: No locks required. The Local, CMS, and/or CPU locks may be held.
Control parameters: No requirements

Programming requirements

None.

Restrictions

Except for the TCB, all input parameters to this macro can reside in storage above 16 megabytes.

While in process-must-complete mode, a task must not:
  • Issue STATUS STOP,SRB or STATUS START,SRB
  • Request the LOCAL lock unconditionally
  • Issue an SVC or invoke services that issue SVCs
  • Issue the WAIT macro or invoke services that issue WAITs
While in process-must-complete mode, a preemptable SRB must not:
  • Request the LOCAL lock unconditionally
  • Pause
  • Suspend

These restrictions also apply to any routine invoked by a program in process-must-complete mode.

Process-must-complete mode is not preserved across a retry from an ESTAE-type routine. However, it is preserved across a retry from an FRR, unless the FRR is an EUT FRR and the environment at the time of the abend was Enabled, Unlocked, and in Task mode.

For the START or STOP parameters, the caller cannot have an EUT FRR established.

Register information

After the caller issues the macro, the system might use some registers as work registers or might change the contents of some registers. When the system returns control to the caller, the contents of these registers are not the same as they were before the macro was issued. Therefore, if the caller depends on these registers containing the same value before and after issuing the macro, the caller must save these registers before issuing the macro and restore them after the system returns control.

When control returns to the caller, the GPRs contain:
Register
Contents
0-1
Used as work registers by the system
2-13
Unchanged
14
Used as a work register by the system
15
Return code
When control returns to the caller, the access registers (ARs) contain:
Register
Contents
0-1
Used as work registers by the system
2-13
Unchanged
14-15
Used as work registers by the system

Performance implications

Using STATUS will degrade performance of the calling program's address space while STATUS runs.

Remaining in process-must-complete mode for an extended period of time will degrade the performance of other programs waiting to use global resources that the program in this mode holds.