Front cover Modernizing Applications with IBM CICS Russell Bonner Sophie Green Ezriel Gross Jim Harrison Debra Scharfstein Will Yates Redpaper IBM Redbooks Modernizing Applications with IBM CICS December 2020 REDP-5628-00 Note: Before using this information and the product it supports, read the information in “Notices” on page v. First Edition (December 2020) © Copyright International Business Machines Corporation 2020. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . .v Trademarks . vi Preface . vii Accompanying education course . vii Authors. viii Now you can become a published author, too! . viii Comments welcome. viii Stay connected to IBM Redbooks . ix Chapter 1. Introduction. 1 1.1 CICS and the hybrid multi-cloud . 2 1.2 Migrating to the hybrid multi-cloud . 2 1.2.1 Maintaining the status quo . 2 1.2.2 Using cloud-native applications. 2 1.2.3 Modernizing existing applications . 3 1.3 CICS Hello World COBOL example . 3 Chapter 2. IBM CICS application development . 5 2.1 Application development in CICS . 6 2.1.1 Batch processing versus online transaction processing . 6 2.1.2 Programming paradigm. 6 2.1.3 Basic architecture of a CICS program. 7 2.1.4 CICS resources. 9 2.2 CICS sample application. 10 2.3 CICS modernization . 11 2.4 CICS built-in transactions . 12 2.4.1 CICS Execute Command Interpreter . 12 2.4.2 CICS Execution Diagnostic Facility. 13 Chapter 3. Coding applications to run in IBM CICS. 15 3.1 Introduction to the EXEC CICS application programming interface . 16 3.2 CICS API example . 17 3.3 COBOL translator . 18 3.4 Response codes . 20 Chapter 4. Programming an IBM CICS application in COBOL . 21 4.1 Presentation logic . 22 4.1.1 Communication area. 22 4.1.2 First time through processing . 24 4.1.3 Function evaluation. 25 4.1.4 Field validation and link to PAYBUS . 26 4.1.5 Checking the return code from the link . 27 4.1.6 Remaining presentation logic processing . 28 4.2 Business logic . 29 4.2.1 COMMAREA and special processing . 30 4.2.2 Request analysis. 30 4.2.3 Updating a record . 32 4.2.4 Adding a record. 33 © Copyright IBM Corp. 2020. iii 4.2.5 Deleting a request. 34 4.2.6 Browsing forward and backward. 34 Chapter 5. Modernization by using channels and containers . 37 5.1 Examining the existing functions. 38 5.2 Introducing channels and containers . 38 5.3 From COMMAREA to channels and containers . 39 5.4 Working with CICS programs in Visual Studio Code. 42 5.5 CICS and Zowe. 44 Chapter 6. Modernizing applications with Java . 47 6.1 Why use Java with CICS. 48 6.2 Writing CICS Java applications. 48 6.2.1 Hello World code sample . 49 6.2.2 Moving the Payroll application to Java . 49 6.3 Unit testing Java applications . 51 6.3.1 Writing a basic unit test. 51 6.3.2 Mocking with CICS applications . 52 6.3.3 JCICSX remoting . 52 Chapter 7. Modern IBM CICS application programming features . 55 7.1 Asynchronous programming . 56 7.1.1 Asynchronous programming analogy . 56 7.1.2 Asynchronous programming principles. 57 7.2 Event processing. 60 7.2.1 Event processing in CICS . 60 7.2.2 Event processing example . 62 7.3 Link to WebSphere Liberty . 63 Chapter 8. DevOps and IBM CICS . 67 8.1 Introduction to DevOps . 68 8.2 DevOps on IBM Z with CICS applications. 68 8.2.1 The integrated development environment and debugging . 69 8.2.2 Source code management . 70 8.2.3 Build solutions. ..