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

    Converts an unconnected socket into a passive socket and
    indicates that the kernel should accept incoming connection
    requests directed to the socket.
    Sets the maximum limit of outstanding connection requests for a
    socket that is connection-oriented.
    The $QIO equivalent is the IO$_SETMODE function.
    Format
      int listen  ( int s, int backlog );

  Additional Information (explode) :

• Arguments
• Description
• Return Values
• Errors