/sys$common/syshlp/helplib.hlb POSIX Threads, TIS routines, tis_setcancelstate, Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 state

    State of general cancelability to set for the calling thread.
    Valid state values are as follows:

       PTHREAD_CANCEL_ENABLE
       PTHREAD_CANCEL_DISABLE

 oldstate

    Receives the value of the calling thread's previous cancelability
    state.