On the Pawsey documentation they refer to the --cpus-per-task as the max number of threads in an OpenMP application: "--cpus-per-task=<c> (or -c <c>): specifies the number of cores assigned to each process (or task related to the --ntasks option). For OpenMP jobs, and multithreaded programs in general, this implies each task may have up to c threads running in parallel. The value for the --cpus-per-task should correspond to the one associated with the OMP_NUM_THREADS variable for OpenMP applications."