Application Programming Interfaces

The CICS® Transaction Gateway and CICS Universal Client support the integration of CICS systems and client systems. They have a standard set of functions to allow user applications to call CICS programs or initiate CICS 3270 transactions.

Three Application Programming Interfaces (APIs) are available to enable user applications to access and update CICS facilities and data. These are the External Call Interface (ECI), the External Presentation Interface (EPI) and the External Security Interface (ESI).