NISCS_PORT_SERV provides flag bits for PEDRIVER port services:

    o  Setting bits 0 and 1 (hex bitmask value 3) enables data
       checking.

    o  Setting bit 2 (hex bitmask value 4) enables data compression
       on all virtual channels (VCs) to nodes that support
       compression.

    The remaining bits are reserved for future use.

    You can use SCACP to enable data checking or data compression on
    a running system:

      Use the SCACP command SET VC/CHECKSUMMING to specify data
      checking on the VCs to certain nodes.

      Use the SCACP command SET VC/COMPRESSION to specify data
      compression on the VCs to certain nodes.

    For more information, see the SCACP documentation in the
    VSI OpenVMS System Management Utilities Reference Manual.

    Changing the setting of NISCS_PORT_SERV does not require a
    reboot.  Furthermore, this parameter applies to all virtual
    circuits between the node on which it is set and other nodes
    in the VMScluster.

    NISCS_PORT_SERV has the DYNAMIC and AUTOGEN attributes.