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

 type

    The cancelability type to set for the calling thread. The
    following are valid values:

       PTHREAD_CANCEL_DEFERRED
       PTHREAD_CANCEL_ASYNCHRONOUS

 oldtype

    Returns the previous cancelability type.