3.11 OMP_STACKSIZE – Set default thread stack size

Description:

Set the default thread stack size in kilobytes, unless the number is suffixed by B, K, M or G, in which case the size is, respectively, in bytes, kilobytes, megabytes or gigabytes. This is different from pthread_attr_setstacksize which gets the number of bytes as an argument. If the stack size cannot be set due to system constraints, an error is reported and the initial stack size is left unchanged. If undefined, the stack size is system dependent.

Reference:

OpenMP specification v4.5, Section 4.7