OMP_MAX_ACTIVE_LEVELS (GNU libgomp)

### 4.8 `OMP_MAX_ACTIVE_LEVELS` – Set the maximum number of nested parallel regions ¶

ICV: max-active-levels-var
Scope: data environment
Description:

  Specifies the initial value for the maximum number of nested parallel regions. The value of this variable shall be a positive integer. If undefined, then if `OMP_NESTED` is defined and set to true, or if `OMP_NUM_THREADS` or `OMP_PROC_BIND` are defined and set to a list with more than one item, the maximum number of nested parallel regions is initialized to the largest number supported, otherwise it is set to one.

See also:

  `omp_set_max_active_levels` – Limits the number of active parallel regions, `OMP_NESTED` – Nested parallel regions, `OMP_PROC_BIND` – Whether threads may be moved between CPUs, `OMP_NUM_THREADS` – Specifies the number of threads to use

Reference:

  OpenMP specification v4.5, Section 4.9