Library /sys$common/syshlp/nclhelp.hlb set, lapb, link, poll_timer  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: Implementation specific   Value: Supplied by profile

    Maximum period in seconds that may elapse without frames being
    exchanged on the Data Link. On expiration, an RR(P) is sent to
    elicit a response from the other end.