The OMP_CANCELLATION environment variable sets the initial value of the cancel-var ICV.
The value of this environment variable must be one of the following:
true | false
If set to true, the effects of the cancel construct and of cancellation points are enabled and cancellation is activated. If set to false, cancellation is disabled and the cancel construct and cancellation points are effectively ignored. The behavior of the program is implementation defined if OMP_CANCELLATION is set to neither true nor false.