Starting a parallel session on an ISC TCP/IP link from IMS
From IMS, you start an ISC TCP/IP parallel session with CICS® by issuing the /OPNDST NODE command.
- Before you can start an ISC TCP/IP session with CICS, the connection must be defined in IMS, IMS Connect, and CICS as described in Setting up an ISC TCP/IP connection with CICS.
- In IMS, the ISC terminal must be defined to use TCP/IP. If the terminal is not defined to use TCP/IP, IMS attempts to start the session by using VTAM®.
- The node name that identifies the target CICS subsystem.
- The user name of the parallel session.
- For sessions that use dynamically defined terminals, the name of the ETO logon descriptor that defines the terminal attributes of the connection and identifies the IMS Connect instance that provides TCP/IP support.
You can find the node name on the NODE keyword of the ISC statement that defines the target CICS subsystem to IMS Connect.
For sessions that use statically defined terminals, the node name is also defined to IMS on the ISCTCPIP keyword of the DFSDCxxx PROCLIB member, which defines the terminal as using TCP/IP, as well as the NAME keyword of the TERMINAL system definition macro.
The requirements for specifying the user name of a parallel session differ depending on whether the parallel sessions and the ISC terminals are statically or dynamically defined.
If either IMS or CICS uses static definitions, the user name that you specify on the /OPNDST NODE command must match the corresponding value in the static definitions. In IMS, the user name of a statically defined parallel session is defined by the NAME keyword of the SUBPOOL system definition macro. In CICS, the user name is defined by either the IPCONN name or the APPLID keyword of the IPCONN resource definition.
If IMS dynamically defines the ISC terminals, the user name is specified only on the USER keyword of the /OPNDST NODE command in the IMS system.
If the CICS autoinstall function is active in the CICS subsystem and the parallel session is started from IMS, CICS uses the user name defined in IMS to name the IPCONN resource. However, if the user name is greater than four characters in length, CICS uses only the last four characters.
The user name specified in the USER keyword of the /OPNDST NODE command can be up to 8 characters. However, CICS uses only the last four characters of the user name if the IPCONN autoinstall program is active in CICS.
ETO logon descriptors define the attributes of the dynamic terminals that are used for the ISC connection to CICS, including the name of the IMS Connect instance that provides TCP/IP support.
Specifying a logon descriptor on the /OPNDST NODE command is optional. If the LOGOND keyword is not specified and a parallel session is not already open, the value of the NODE keyword is used to search for a logon descriptor. Alternatively, the name of the logon descriptor can be provided by a Logon exit routine (DFSLGNX0).
If a parallel session is already open on a node and a different logon descriptor is specified than was used to start the first parallel session, the /OPNDST NODE command is rejected.
If the logon descriptor that is specified on the /OPNDST NODE command does not specify TCP/IP support, IMS attempts to open the session as a VTAM node.
The /OPNDST NODE command is the only way to start an ISC TCP/IP parallel session with CICS from IMS.