CICS front-end transaction types supported by ISC over TCP/IP

As a front-end system, CICS® supports only the asynchronous START and RETRIEVE interface for ISC TCP/IP connections with IMS.

Consequently, CICS application programs must use the IMS non-response or non-conversational mode transactions. CICS application programs cannot use either the synchronous or asynchronous SEND and RECEIVE interfaces with TCP/IP. To use the CICS asynchronous SEND and RECEIVE interface or CICS synchronous distributed transaction processing (DTP) with ISC, the ISC connections must use VTAM®.

When IMS is the front-end system, the transaction flow from IMS to CICS on an ISC TCP/IP connection is also asynchronous, the same as it is on an ISC VTAM connection.