THREADSTACK64 (AMODE 64 only)

Derivation: THREAD level STACK storage for AMODE 64

THREADSTACK64 controls the allocation of the thread's stack storage for AMODE 64 applications, except for the initial thread in a multithreaded environment.

The default value for AMODE 64 applications is THREADSTACK64(OFF,1M,1M,128M).

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Syntax

                         .-OFF-.                                
>>-+-THREADSTACK64-+--(--+-----+--,--initial--,--increment--,--->
   '-TS64----------'     '-ON--'                                

>--maximum--)--------------------------------------------------><
OFF
Indicates that the allocation suboptions of the STACK64 runtime option are used for thread stack allocation. Any other suboption specified with THREADSTACK64 is ignored.
ON
Controls the stack allocation for each thread, except the initial thread, in a multithreaded environment.
initial
Determines the size of the initial stack segment. The storage is contiguous. This value is specified as nM bytes of storage.
increment
Determines the minimum size of any subsequent increment to the stack area. This value is specified as nM bytes of storage. The actual amount of allocated storage is the larger of two values— increment or the requested size—rounded up to the nearest multiple of 1MB.

If you specify increment as 0, only the amount of the storage needed at the time of the request, rounded up to the nearest multiple of 1MB, is obtained.

The requested size is the amount of storage a routine needs for a stack frame.

maximum
Specifies the maximum stack size. This value is specified as nM bytes of storage. When the maximum size is less than the initial size, initial is used as the maximum stack size.

Usage notes

  • The 1 MB guard page is not included in any of the sizes.
  • The maximum thread stack segment is the maximum of THREADSTACK64 initial and maximum sizes.
  • The default value of 128 MB for the maximum stack size of the STACK64 and THREADSTACK64 runtime options can cause excessive use of system resources (such as real storage) when running a multithreaded application that creates many pthreads. For such applications, it is recommended to use the Language Environment® Storage Report (RPTSTG runtime option) to determine your application's actual pthread stack storage usage, and then use the THREADSTACK64 runtime option to set the maximum stack size to a value closer to the actual usage.

For more information

For more information about heap storage and heap storage tuning with storage report numbers, see z/OS Language Environment Programming Guide.

Parent topic: Using the Language Environment runtime options