Operating ISC TCP/IP connections

Operational tasks for an ISC TCP/IP connection in one segment of an ISC TCP/IP connection impacts the connection in the other segments. Also, general operational tasks in the IMS system are also likely to impact any ISC TCP/IP connections.

Under normal circumstances, you start, stop, and restart an ISC link from IMS by using the /OPNDST and /QUIESCE type-1 commands. The /OPNDST command starts or restarts an ISC link to a remote CICS® subsystem. The /QUIESCE command stops an ISC link to a remote CICS subsystem after any in-progress work completes.

Occasionally, you might find it necessary to stop an ISC TCP/IP link from IMS Connect, such as might be the case if a link is shut down from IMS, but IMS Connect fails to properly clean up its resources that support the link. In IMS Connect, you can shut down an ISC link or you can shutdown a TCP/IP connection to a remote CICS subsystem. When you shut down an ISC link in IMS Connect, all sessions on that link are terminated, but communications with the remote CICS subsystem might continue on other ISC links. If you shutdown a connection to a remote CICS subsystem, all ISC links that connect to that remote CICS subsystem are stopped, including all sessions on those links.

In rare extreme cases, you could also stop an ISC link by shutting down communications between SCI and either IMS or IMS Connect; however, doing so would stop all communications in IMS or IMS Connect that require SCI, not just those that use ISC TCP/IP links.