NISCS_PORT_SERV

   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.

   Starting with OpenVMS Version 7.3-1, you can use the SCACP
   command SET VC/CHECKSUMMING to specify data checking on the VCs
   to certain nodes. You can do this on a running system. (For more
   information, see the SCACP documentation in the VSI OpenVMS System
   Management Utilities Reference Manual.

   Starting with OpenVMS Version 8.3, you can also use the SCACP
   command SET VC/COMPRESSION to specify data compression on the
   on the VCs to certain nodes. You can use SCACP to enable either
   data checking or data compression on a running system. (See the
   SCACP documentation in the the VSI OpenVMS System Management
   Utilities Reference Manual for more information. Also starting
   with OpenVMS Version 8.3, the NISCS_PORT_SERV system parameter
   is dynamic, that is, changing the setting of this parameter no
   longer requires a reboot. Furthermore, this parameter applies
   to all virtual circuits between the node on which it is set and
   other nodes in the cluster.

   NISCS_PORT_SERV has the DYNAMIC and AUTOGEN attributes.