6.6  OMP_STACKSIZE

The OMP_STACKSIZE environment variable controls the size of the stack for threads created by the OpenMP implementation, by setting the value of the stacksize-var ICV. The environment variable does not control the size of the stack for an initial thread.

The value of this environment variable takes the form:

size | sizeB | sizeK | sizeM | sizeG

where:

• size is a positive integer that specifies the size of the stack for threads that are created by the OpenMP implementation.
• B, K, M, and G are letters that specify whether the given size is in Bytes, Kilobytes (1024 Bytes), Megabytes (1024 Kilobytes), or Gigabytes (1024 Megabytes), respectively. If one of these letters is present, there may be white space between size and the letter.

If only size is specified and none of B, K, M, or G is specified, then size is assumed to be in Kilobytes.

The behavior of the program is implementation defined if OMP_STACKSIZE does not conform to the above format, or if the implementation cannot provide a stack with the requested size.

Examples:  

 
setenv OMP_STACKSIZE 2000500B 
setenv OMP_STACKSIZE "3000 k " 
setenv OMP_STACKSIZE 10M 
setenv OMP_STACKSIZE " 10 M " 
setenv OMP_STACKSIZE "20 m " 
setenv OMP_STACKSIZE " 1G" 
setenv OMP_STACKSIZE 20000
  

Cross References

• stacksize-var ICV, see Section 2.5 on page 171.