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

       tis_read_lock()
       tis_read_unlock()
       tis_rwlock_destroy()
       tis_rwlock_init()
       tis_write_lock()
       tis_write_trylock()
       tis_write_unlock()