CICS Transaction Server for z/OS 5.4 Intercommunication Guide IBM Note Before using this information and the product it supports, read the information in “Notices” on page 359. This edition applies to the IBM CICS® Transaction Server for z/OS® Version 5 Release 4 (product number 5655-Y04) and to all subsequent releases and modifications until otherwise indicated in new editions. © Copyright International Business Machines Corporation 1974, 2020. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents About this PDF......................................................................................................ix Chapter 1. CICS intercommunication..................................................................... 1 Intercommunication methods.....................................................................................................................1 Communication between systems.........................................................................................................1 Multiregion operation............................................................................................................................. 1 Using CICS intercommunication............................................................................................................ 2 Intercommunication facilities......................................................................................................................4 Function shipping................................................................................................................................... 6 Asynchronous processing...................................................................................................................... 6 Transaction routing.................................................................................................................................6 Distributed program link (DPL)...............................................................................................................7 Distributed transaction processing (DTP)..............................................................................................7 Transaction tracking.....................................................................................................................................7 Association data..................................................................................................................................... 8 ISC and IPIC intercommunications facilities............................................................................................ 15 Intercommunication using IP interconnectivity..................................................................................15 Intersystem communication over SNA................................................................................................18 Multiregion operation................................................................................................................................ 23 Intercommunication facilities available using MRO............................................................................23 Cross-system multiregion operation (XCF/MRO)................................................................................ 23 Applications of multiregion operation................................................................................................. 27 Conversion from a single-region system............................................................................................. 29 CICS function shipping.............................................................................................................................. 29 Overview of function shipping..............................................................................................................29 Design considerations for Function Shipping...................................................................................... 30 The mirror transaction and transformer program............................................................................... 33 Function shipping examples................................................................................................................ 36 Asynchronous processing..........................................................................................................................39 Overview of asynchronous processing................................................................................................ 39 Asynchronous processing methods.....................................................................................................40 Asynchronous processing using START and RETRIEVE commands................................................... 41 System programming considerations..................................................................................................46 Asynchronous processing examples................................................................................................... 47 CICS dynamic routing................................................................................................................................ 49 Two routing models..............................................................................................................................51 Two routing programs.......................................................................................................................... 53 CICS transaction routing............................................................................................................................54 Overview of transaction routing...........................................................................................................54 Terminal-initiated transaction routing.................................................................................................55 Traditional routing of transactions started by ATI...............................................................................58 Routing transactions invoked by START commands........................................................................... 65 Allocation of remote APPC connections..............................................................................................72 The relay program................................................................................................................................ 75 Basic mapping support (BMS)..............................................................................................................75 Using the routing transaction, CRTE.................................................................................................... 76 System programming for transaction routing......................................................................................77 CICS distributed program link................................................................................................................... 77 Overview of DPL................................................................................................................................... 77 Statically routing DPL requests............................................................................................................78 iii Dynamically routing DPL requests.......................................................................................................81 Daisy-chaining of DPL requests........................................................................................................... 83 Limitations of DPL server programs.....................................................................................................83 Intersystem queuing............................................................................................................................ 84 Examples of DPL...................................................................................................................................84 Distributed transaction processing........................................................................................................... 85 Overview of DTP................................................................................................................................... 85 Advantages over function shipping and transaction routing...............................................................86 Why distributed transaction processing?............................................................................................ 86 DTP’s place in the CICS intercommunication facilities....................................................................... 87 What is DTP?.........................................................................................................................................87 Distributed processes.......................................................................................................................... 90 Maintaining data integrity.................................................................................................................... 91 Designing distributed processes..........................................................................................................92 What is a conversation and what makes it necessary?....................................................................... 97 MRO or APPC for DTP?......................................................................................................................