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| OPENMP API Specification: Version 5.0 November 2018

6.9  OMP_NESTED

The OMP_NESTED environment variable controls nested parallelism by setting the initial value of the max-active-levels-var ICV. If the environment variable is set to true, the initial value of max-active-levels-var is set to the number of active levels of parallelism supported by the implementation. If the environment variable is set to false, the initial value of max-active-levels-var is set to 1. The behavior of the program is implementation defined if the value of OMP_NESTED is neither true nor false.

If both the OMP_NESTED and OMP_MAX_ACTIVE_LEVELS environment variables are set, the value of OMP_NESTED is false, and the value of OMP_MAX_ACTIVE_LEVELS is greater than 1, the behavior is implementation defined. Otherwise, if both environment variables are set then the OMP_NESTED environment variable has no effect.

The OMP_NESTED environment variable has been deprecated.

Example:  

 
setenv OMP_NESTED false  

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