Which CICS image or adapter should I use, and why does CICS return 500?

Use Mainframe connectors in OL Integration with the generator that matches the CICS interface, not a nearby Docker tag.

Images / generators

• CICS COMMAREA / program call — RPC-style CICS connector and the matching spring-java / RPC generator.
• CICS TS / containers — use the CICS TS (or documented CICS-container) runtime when the program uses containers, not COMMAREA. Sending an array in a container with a COMMAREA-style adapter yields empty array data.
• Do not mix mainframe-cics-ts with a generic main-frame-rpc-spring-java-rest image for the same interface.

HTTP 500 from CICS

Often the CICS Web Interface / adapter is failing (program abend, TSMODEL, container size, 32KB COMMAREA). Check CICS logs, not only Hub. DEFINE TSMODEL is only required for adapter versions that used it; newer CICS adapters may not.