Below the SNA interface

To design high-performance distributed processes, you need some understanding of the SNA protocols and corresponding data flow control (DFC) indicators that CICS® uses for DTP, and how the DFC indicators relate to the CICS commands and options. In addition, you need this knowledge to understand the CICS trace.

Except for some commands that can cause transmissions against the flow (such as ISSUE SIGNAL), the conversation flow and indicators set are dictated by the transaction currently in send state (state 2).