VMS Help TCPIP Services, Programming Interfaces, Sockets API, listen(), Errors  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    EBADF              The socket descriptor is invalid.
    EDESTADDRREQ       The socket is not bound to a local address,
                       and the protocol does not support listening on
                       an unbound socket.
    EINVAL             The socket is already connected, or the socket
                       is shut down.
    ENOBUFS            The system has insufficient resources to
                       complete the call.
    ENOTSOCK           The socket descriptor is invalid.
    EOPNOTSUPP         The referenced socket is not of a type that
                       supports the operation listen().