A user application can call a CICS® program in a CICS server by using an ECI request. The user application can connect to several CICS servers at the same time and have several called CICS programs running concurrently. The CICS programs must be COMMAREA-based programs that can be called using the CICS command
CICS programs that are invoked by an ECI request must follow the rules for distributed program link (DPL) requests. For information on DPL requests see the CICS Application Programming Guide. For information on the API restriction for DPL requests refer to Appendix G of the CICS Application Programming Reference.