Paging memory

Saturation state

Message: EXC0873 NEW PAGING MEMORY SATURATION LEVEL=i
where i is a digit in the range 0 through 3 indicating the saturation level.

Level	Effects on system	Operator action
0	Normal system processing	None
1	Warning of a possible saturation state (if the PAGING-SATURATION-WARNING-LIMIT parameter is specified, see "PAGING-SATURATION-WARNING-LIMIT n [,UNIT=4KB / MB ]" in section "Memory management (MEMORY)")	See "Saturation prevention measures"
2	Batch jobs requesting class 6 memory are rolled out.1) No new jobs will be started.	Operator must try to abort jobs or to dynamically extend the pagingarea with EXTEND-PAGING-AREA
3	Interactive and batch jobs requesting class 6 memory are rolled out. The following message is issued to SYSOUT of dialog jobs. EXC0844 TASK TEMPORARILY HELD DUE TO PAGING DEVICE SATURATION. TASK WILL BE CONTINUED AUTOMATICALLY The TCB addresses of the jobs are managed in a queue. There they are arranged as follows: interactive jobs precede batch jobs high-priority jobs precede low-priority jobs jobs of the same priority are arranged according to the number of relocated pages (jobs with fewer relocated pages come first) No new jobs will be started.	Operator must try to abort jobs or to dynamically extend the paging area with EXTEND-PAGING-AREA A deadlock or system crash may result.

¹⁾ The job’s class 6 memory is saved to a temporary disk file (EAM), and then released.
   This job must fulfill the following conditions:

• the class 6 memory request does not refer to a common memory pool for several jobs

• the job is not associated with a serialization identifier

• the job has not disabled any file pages

Desaturation

Level	Effects on system	Operator action
1	Level=1 merely indicates that the first job in the queue has been transferred back but there are still further rolled-out jobs.	None
0	All rolled-out jobs are processed. Jobs can be started again.	None

Saturation prevention measures

The occurrence of a saturation condition indicates that the system is overloaded.

If the system is affected by recurrent saturation, then the system configuration is inadequate or the measures taken to reduce the load are insufficient.

• Increase the paging memory.

• Ensure that a sufficiently large paging memory is set up during the system initialization phase of subsequent sessions (parameter service)

• Check the load reduction measures.

Examples for the reduction of a system’s paging memory requirements (if an extension is not desired)

• Unload large applications or programs

• Considerably reduce the number of tasks in the system

Settings for threshold values and warnings

The threshold values for the saturation states and the warnings for the saturation levels can be configured in the startup parameter service, parameter set MEMORY, see section "Memory management (MEMORY)".