In z/OS V2R1 support was added to monitor usage of kernel storage used for stacks and available below the bar kernel private storage. This involves Health Checks (USS_KERNEL_PVTSTG_THRESHOLD, USS_KERNEL_PVTSTG_THRESHOLD) to determine when a shortage of either occurs and the issuing of messages (BPXH071E, BPXH072E) to alert operations of the shortage. There is a new DISPLAY OMVS console command option (STORAGE|ST and STORAGE|ST,RESET) to display a list of processes using more than 50 stack cells (in message BPXO075I).
Here is some information about the health checks.
Health Check USS_KERNEL_PVTSTG_THRESHOLD monitors the current usage of UNIX System Services kernel private storage below the bar against a suggested threshold. At kernel initialization 80% of the available region is designated for stack cell pool cells and the remaining 20% for kernel and system usage. Because the stack cell pool is only extended as needed all of the storage that is designated for stack cell might not be allocated. If the allocation of storage designated for kernel and system usage overflows into the storage designed for stack cells, the number of stack cells that can be allocated is reduced. Reducing the number of stack cells that can be allocated can reduce the system-wide UNIX workload.
Health Check USS_KERNEL_STACKS_THRESHOLD monitors the current usage of z/OS UNIX kernel stacks cell pool cells against a suggested threshold. If the number of kernel stack cell pool cells in use reaches the system maximum, additional cells cannot be allocated and system calls that use the kernel address space are disallowed. By monitoring stack cell usage installations might be able to prevent impacts to critical workloads by quiescing noncritical workloads before the supply of stack cells is exhausted.
See the MVS System Messages manual and the Health Check manual for information on the displays and fields.
Here is an example of an exception for the USS_KERNEL_PVTSTG_THRESHOLD health check and the OMVS display with the STORAGE option. In z/OS V2R1, the percentage of usage for private storage can be over 100% if the allocation is more than the determined maximum available value at kernel initialization time, and has overflowed into the storage designated for stack cells.
*HZS0003E CHECK(IBMUSS,USS_KERNEL_PVTSTG_THRESHOLD):
*BPXH072E The z/OS UNIX System Services kernel usage of monitored below
*the bar private storage has exceeded the check threshold of 85%.
*Currently 286519296 of 281202688 bytes (101%) of monitored
*private storage has been allocated.
D OMVS,ST
BPXO075I 08.20.57 DISPLAY OMVS
OMVS 0012 ACTIVE OMVS=(00,Z1)
KERNEL STORAGE USAGE
PRIVATE STORAGE:
CURRENT USAGE MAXIMUM AVAILABLE HIGH WATER REGION SIZE
286109696 281202688 288829440 1419747328
STACK CELLS:
CURRENT USAGE MAXIMUM CELLS HIGH WATER
1554 30512 1675
PROCESS STACK CELL USAGE
USER JOBNAME ASID PID PPID STATE THREADS STACKS
WSWEBSRV WSWEBT10 0132 50397278 1 HK------ 156 306
WSWEBSRV WSWEBT11 014B 16842873 1 HK------ 154 304
WSW2WEBS WSWEBZ1P 0127 65618 1 HK------ 46 86
SKRBKDC SKRBKDC 03B6 66649 1 HR------ 90 57
Here is an example of exceptions for the USS_KERNEL_PVTSTG_THRESHOLD and USS_KERNEL_STACKS_THRESHOLD health checks and the OMVS display with the STORAGE option.
*HZS0003E CHECK(IBMUSS,USS_KERNEL_PVTSTG_THRESHOLD):
BPXH072E The z/OS UNIX System Services kernel usage of monitored below
the bar private storage has exceeded the check threshold of 85%.
Currently 1168437244 of 291065036 bytes (401%) of monitored
private storage has been allocated.
*HZS0002E CHECK(IBMUSS,USS_KERNEL_STACKS_THRESHOLD):
BPXH071E The z/OS UNIX System Services kernel usage of autodata
(stack) cellpool cells has exceeded the check threshold of 85%.
Currently 17794 of 20303 cells (87%) are in use.
D OMVS,ST
BPXO075I 22.17.52 DISPLAY OMVS
OMVS 0011 ACTIVE OMVS=(R1,ST)
KERNEL STORAGE USAGE
PRIVATE STORAGE:
CURRENT USAGE MAXIMUM AVAILABLE HIGH WATER REGION SIZE
1168437244 291065036 1168437244 1469030400
STACK CELLS:
CURRENT USAGE MAXIMUM CELLS HIGH WATER
17794 20303 17794
PROCESS STACK CELL USAGE
USER JOBNAME ASID PID PPID STATE THREADS STACKS
WEBSRV IMWEBSRV 003E 65558 1 HK------ 46 86
The following are some displays from our z/OS V2R1 environment.
Here is successful information from our health check, USS_KERNEL_PVTSTG_THRESHOLD. We used the default 85% threshold.
NP NAME CheckOwner State Status
USS_KERNEL_PVTSTG_THRESHOLD IBMUSS ACTIVE(ENABLED) SUCCESSFUL
CHECK(IBMUSS,USS_KERNEL_PVTSTG_THRESHOLD)
SYSPLEX: UTCPLXJ8 SYSTEM: JF0
START TIME: 10/29/2013 13:45:17.624238
CHECK DATE: 20120801 CHECK SEVERITY: LOW-DYNAMIC
CHECK PARM: PVTSTG(85%)
BPXH003I z/OS UNIX System Services was initialized using OMVS=(00,JF),
where each 2-character item is a BPXPRMxx suffix.
END TIME: 10/29/2013 13:45:17.624366 STATUS: SUCCESSFUL
Here is successful information from our health check, USS_KERNEL_STACKS_THRESHOLD. We used the default 85% threshold.
NP NAME CheckOwner State Status
USS_KERNEL_STACKS_THRESHOLD IBMUSS ACTIVE(ENABLED) SUCCESSFUL
CHECK(IBMUSS,USS_KERNEL_STACKS_THRESHOLD)
SYSPLEX: UTCPLXJ8 SYSTEM: JF0
START TIME: 10/29/2013 13:45:28.468355
CHECK DATE: 20120801 CHECK SEVERITY: LOW-DYNAMIC
CHECK PARM: STACKS(85%)
BPXH003I z/OS UNIX System Services was initialized using OMVS=(00,JF),
where each 2-character item is a BPXPRMxx suffix.
END TIME: 10/29/2013 13:45:28.468453 STATUS: SUCCESSFUL
Here is information from the ‘D OMVS,STORAGE’ display in our environment.
D OMVS,STORAGE
BPXO075I 12.43.38 DISPLAY OMVS 169
OMVS 0012 ACTIVE OMVS=(00,JF)
KERNEL STORAGE USAGE
PRIVATE STORAGE:
CURRENT USAGE MAXIMUM AVAILABLE HIGH WATER REGION SIZE
73093119 285815603 77697023 1442816000
STACK CELLS:
CURRENT USAGE MAXIMUM CELLS HIGH WATER
1375 31012 1482
PROCESS STACK CELL USAGE
USER JOBNAME ASID PID PPID STATE THREADS STACKS
WSWEBSRV WSWEBP10 017D 131129 1 HK------ 156 306
WSWEBSRV WSWEBP11 0177 50462767 1 HK------ 154 304
WAS5SSR2 WSP1S2FS 0257 33685653 67240108 HR------ 15 125
WAS5SSR3 WSP1S3FS 0265 131304 16908519 HR------ 151 121
WAS5SSR1 WSP1S1FS 01B9 33685714 67240147 HRI----- 38 118
If there are no processes using 50 or more space switched stack cells an indication will be made in the PROCESS STACK CELL USAGE section.
D OMVS,STORAGE
BPXO075I 12.43.38 DISPLAY OMVS 592
OMVS 0012 ACTIVE OMVS=(00,JG)
KERNEL STORAGE USAGE
PRIVATE STORAGE:
CURRENT USAGE MAXIMUM AVAILABLE HIGH WATER REGION SIZE
49905660 292318412 53841916 1475321856
STACK CELLS:
CURRENT USAGE MAXIMUM CELLS HIGH WATER
164 31718 164
PROCESS STACK CELL USAGE
USER JOBNAME ASID PID PPID STATE THREADS STACKS
NO PROCESSES FOUND USING 50 OR MORE SPACE SWITCHED STACK CELLS.
There is a reset option (D OMVS,STORAGE,RESET) that will reset the HIGH WATER usage for PRIVATE STORAGE and STACK CELLS to the CURRENT USAGE.
D OMVS,ST,RESET
BPXO075I 14.44.45 DISPLAY OMVS 643
OMVS 0012 ACTIVE OMVS=(00,JF)
KERNEL STORAGE USAGE
PRIVATE STORAGE:
CURRENT USAGE MAXIMUM AVAILABLE HIGH WATER REGION SIZE
72073215 285815603 72073215 1442816000
STACK CELLS:
CURRENT USAGE MAXIMUM CELLS HIGH WATER
1357 31012 1357
PROCESS STACK CELL USAGE
USER JOBNAME ASID PID PPID STATE THREADS STACKS
WSWEBSRV WSWEBP10 017D 131129 1 HK------ 156 306
WSWEBSRV WSWEBP11 0177 50462767 1 HK------ 154 304
WAS5SSR2 WSP1S2FS 0257 33685653 67240108 HR------ 15 125
WAS5SSR3 WSP1S3FS 0265 131304 16908519 HR------ 151 121
WAS5SSR1 WSP1S1FS 01B9 33685714 67240147 HRI----- 38 118
WSWEBSRV WSWEBJFP 017E 131132 1 HK------ 44 84
Author: Alfred Lease