OpenMP Environment Variables - Oracle® Solaris Studio 12.4: OpenMP API User's Guide

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2.2 OpenMP Environment Variables

The OpenMP specification defines several environment variables that control the execution of OpenMP programs. For details, refer to the OpenMP 4.0 specification at http://openmp.org. Also see Chapter 9, OpenMP Implementation-Defined Behaviors for information about the implementation of OpenMP environment variables in Oracle Solaris Studio.

Oracle Solaris Studio supports additional environment variables which are not part of the OpenMP specification, are summarized in Oracle Solaris Studio Environment Variables.

Note - Starting with Oracle Solaris Studio 12.4, the default number of threads used for an OpenMP program is equal to the number of cores on the machine, capped at 32. This number can be changed by setting the OMP_NUM_THREADS environment variable prior to running the program, or by calling the omp_set_num_threads() routine, or by using the num_threads clause on a parallel directive.