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

    shut  [node node-id] session control

    Places session control in the shut state. In this state no
    further connection requests are honored. It continues to service
    existing connections. When all connections have been closed by
    their clients, it is placed in the off state.