VMS Help POSIX Threads, TIS routines, tis_cond_broadcast, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    When threads are not present, this routine has no effect.

    When threads are present, this routine unblocks all threads
    waiting on the specified condition variable cond.

    For further information about actions when threads are present,
    refer to the pthread_cond_broadcast() description.