IP interconnectivity (IPIC)

IPIC provides ECI access to CICS® applications over the TCP/IP protocol, supporting both COMMAREA and CICS channel applications and two phase commit. CICS channels and containers allow you to send and receive more than 32 KB of application data in a single ECI request.

Transactional support

IPIC supports two-phase commit XA transactions in both local and remote modes.

For information about the transaction types supported by the IPIC protocol when using CICS Transaction Gateway to connect to different CICS servers see Which protocol can be used?

Connections to CICS

For IPIC communications between CICS Transaction Gateway and CICS Transaction Server V4.1 (or higher), up to two sockets are used for each IPIC connection. If the IPIC connection is defined to use a maximum of one session, a single socket is used. The use of multiple sockets is indicated by a Gateway daemon log message, which is generated when the connection is established.

For IPIC communications between CICS Transaction Gateway and CICS Transaction Server V3.2 or IBM® TXSeries® systems, one socket is used for each IPIC connection.

If one or more of the socket connections used for an IPIC connection ends unexpectedly, for example, because of a network error, all the sockets are closed and the IPIC connection is released.

Connection sessions

Each IPIC connection can be defined with up to 999 sessions. A single session handles a single request at a time, so that the number of sessions determines the maximum number of simultaneous requests that can be outstanding over an IPIC connection. The number of sessions is defined on both the CICS server IPCONN definition and the CICS TG IPICSERVER definition. If the number of sessions differs on either end of the connection the actual number of sessions established is negotiated when the connection is established.