Figure 2‑1 illustrates the CICS Runtime global architecture.In z/OS CICS applications, all the interactions with the resources managed by CICS are made thru the EXEC CICS API.Listing 2‑1 z/OS CICS callsOn UNIX, the CICS Runtime Preprocessor transforms these EXEC CICS into calls to the CICS Runtime library as shown in Listing 2‑2.Listing 2‑2 CICS Runtime calls
• The Terminal Connection servers (TCP servers: ARTTCPH and ARTTCPL servers): manage user connections and sessions to CICS applications thru 3270 terminals or emulators.
• The Connection Server ARTCNX: manages the user session and some technical transactions relative to security (CSGM: Good Morning Screen, CESN: Sign On, CESF: Sign off).
• The Synchronous Transaction server ARTSTRN: manages standard synchronous CICS transactions that can run simultaneously.
• The Synchronous Transaction servers ARTSTR1: manages CICS synchronous transaction applications that can not run simultaneously but only sequentially (one at a time).
• The Asynchronous Transaction servers ARTATRN and ARTATR1: are similar to the ARTSTRN and ARTSTR1 but for asynchronous transactions started by EXEC CICS START TRANSID statements.
• TS Queue servers ARTTSQ, TMQUEUE and TMQFORWARD: manage the use of CICS Temporary Storage Queues - files managed by CICS thru specific commands.
• Tranclasses (transclasses.desc file)
• Programs (programs.desc file)This file contains a list of all COBOL or C programs invoked thru EXEC CICS START, LINK or XCTL statements.
• TS Queue Model (tsqmodel.desc file)
• Mapsets (mapsets.desc file)These resources are used thru dedicated CICS statements like EXEC CICS SEND or RECEIVE MAP inside COBOL programs.
• Typeterms (typeterms.desc file)