VMS Help POSIX Threads, PTHREAD routines, pthread_rwlock_rdlock, Associated Routines  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       pthread_rwlock_init()
       pthread_rwlockattr_init()
       pthread_rwlock_tryrdlock()
       pthread_rwlock_wrlock()
       pthread_rwlock_unlock()