Modern Mainframe Development: COBOL, Databases, and Next-Generation Approaches

Cover....1

Copyright....6

Table of Contents....7

Foreword....15

Preface....17

What’s Covered....17

Who Is This Book For?....18

The Approach to This Book....18

Conventions Used in This Book....19

Using Code Examples....19

O’Reilly Online Learning....20

How to Contact Us....20

Acknowledgments....21

Part I. Fundamentals of the Mainframe....23

Chapter 1. Why Be a Mainframe Developer?....25

Fear of Disruption....26

Software Is Eating the World....27

COVID-19....29

Government Modernization....30

Future of Mainframe Development....31

Career Opportunities....32

Conclusion....33

Chapter 2. World of the Mainframe....35

What Does “Mainframe” Mean Anyway?....36

A Brief History....36

What Are Punch Cards?....37

Growth of the Mainframe....37

Mainframe Innovation....40

The Terminal....40

Mainframe Challenges....41

Why Have a Mainframe?....42

The OS....43

z/VSE....44

z/TPF....45

z/VM....45

Linux....45

KVM....46

Processor Architecture....46

LPAR....46

Disks....47

Batch and Online Transaction Processing....48

Mainframe Trends....49

The Mainframe “Shop”....49

Conclusion....50

Chapter 3. The Development Environment....51

Accessing a Mainframe....51

TSO....54

ISPF....54

Datasets....56

Main Types of Datasets....57

Sequential File....57

Partitioned Dataset....57

Virtual Storage Access Method....58

Catalogs....59

ISPF and Datasets....60

Creating a File with ISPF....62

System Display and Search Facility....66

Job Control Language....68

Unix System Services....70

Mainframe Tools....70

Modern IDEs....71

IBM Developer for z/OS....71

BMC Compuware Topaz Workbench....72

Che4z....72

Visual Studio Code....73

Standardizing on Visual Studio....78

Simple IDEs....79

Web-Based Editors....79

Development Process....80

Conclusion....81

Chapter 4. The COBOL Language....83

COBOL’s Background, in Brief....83

COBOL Versions....84

Why Use COBOL?....85

COBOL Program Structure: Columns....86

COBOL Program Structure: Divisions....87

IDENTIFICATION DIVISION....88

ENVIRONMENT DIVISION....88

DATA DIVISION....89

PROCEDURE DIVISION....95

Conclusion....110

Chapter 5. File Handling....111

Records and Files....111

Sequential File....112

File Errors....116

WRITE to a File....117

JCL for File-Handling Programs....118

Inventory Update Program....120

File with Multiple Records....124

Variable-Length Records....126

Indexed Files....128

Updating an Indexed File....130

VSAM Files....132

Conclusion....135

Chapter 6. COBOL Tables and Reports....137

Introduction to Tables....137

Tables and Reading Files....140

Multilevel Tables....142

Indexes....146

Searching a Table....146

Binary Search....150

Reports....151

The PROCEDURE DIVISION for Reports....154

Testing a Report....154

Reporting Tools....155

Working with Characters and Strings....156

STRING....158

UNSTRING....159

INSPECT....161

Conclusion....162

Chapter 7. Other Languages and Programming Techniques....163

What Language to Use?....163

Assembler Language....164

Memory....165

Registers....167

Base Displacement Addressing....168

Sample Assembler Language Code....169

Java....169

C and C++....170

PL/I....171

CLIST and REXX....172

REXX Variables....173

REXX Comparisons....174

Control Structures....175

Calling Functions....177

Arrays....179

Object-Oriented COBOL....180

Programming Techniques....180

Copy Member....181

Subprograms....182

Conclusion....183

Chapter 8. Databases and Transaction Managers....185

Information Management System....185

IMS Database Manager....187

IMS Transaction Manager....189

IMS Services and Tools....190

IMS Programming Language....192

Db2 and the Relational Database....195

Benefits of Relational Databases....197

Using Db2....198

Structured Query Language....200

Joins....202

Database Administrator....203

Application Development with Db2....204

Db2 Ecosystem....206

Customer Information Control System....207

Working with the CICS Platform....208

Programming in CICS....209

Conclusion....211

Part II. Modern Topics....213

Chapter 9. DevOps....215

Advantages of DevOps....215

Waterfall Method Model....217

Agile Method....218

Scrum....220

Kanban....221

Lean....223

Agile: It’s Not All About Speed....224

Mainframes and the Challenges for DevOps....225

DevOps Best Practices....226

Configuration Management....227

Issues with DevOps....229

Metrics....230

Mainframe DevOps Tooling....230

Automation....231

CI/CD....232

Zowe....235

BMC Jenkins Plug-ins....237

Zigi....241

Conclusion....244

Chapter 10. Artificial Intelligence....245

What Is AI?....246

Why Use AI?....247

Downsides of AI....248

Machine Learning....250

Binary Classification....251

Multiclass Classification....252

Multilabel Classification....252

Imbalanced Classification....252

Types of Machine Learning....252

Supervised Learning....253

Unsupervised Learning....253

Reinforcement Learning....254

Deep Learning....255

Data....256

Big Data....257

Data Management....258

Log Data....260

Data Wrangling....261

The AI Process....263

Accuracy....265

An AI Demo....266

AI on Z....269

AIOps....270

Conclusion....271

Chapter 11. Robotic Process Automation, and Low-Code and No-Code Systems....273

What Is RPA?....274

The Disadvantages of RPA....276

Macros, Scripts, and APIs....276

Types of RPA....277

Process Methodologies....278

RPA Roles....279

Evaluating RPA Software....280

Process Mining....281

How to Create a Bot....283

Creating a UiPath Bot....283

Creating a Bot for the Mainframe....288

RPA Issues with Mainframes....290

Low-Code and No-Code Systems....291

Conclusion....293

Chapter 12. Mainframe Modernization Strategies....295

Why Modernize?....295

Using a Hybrid Cloud....297

Setting Goals....298

Encapsulating....300

Rehosting or Replatforming....300

Refactoring or Rearchitecting....301

Replacing or Rebuilding....303

Working with the Hyperscalers....304

Amazon Web Services....305

Microsoft....306

Google Cloud....308

Automation Tools....309

Heirloom Computing....310

EvolveWare....311

Advanced’s Automated COBOL Refactoring....312

Astadia....312

Data Migration....312

Conclusion....313

Chapter 13. The Future....315

Innovation of the Mainframe....315

Enterprise Integration....317

The Hybrid Model....319

Mainframe as a Service....320

Conclusion....321

Additional Resources....323

Glossary....325

Index....331

About the Author....348

Colophon....348

Even as spending on digital transformation continues to skyrocket, mainframes nevertheless have major advantages for global enterprises. These systems still process huge amounts of information and allow for highly secure transactions. In this practical book, author Tom Taulli shows software developers how to pursue a hybrid approach by integrating traditional mainframes and applications with modern digital systems.

By the end of this book, you'll have a solid understanding of the mainframe architecture and ecosystem, including core concepts and technologies such as COBOL, REXX, JCL, Db2, VSAM, and CICS. You'll also learn how to blend in newer technologies such as the cloud, AI and machine learning, and microservices. This handbook is indispensable for enterprises looking to thrive in the new digital world.

• Learn strategies and approaches for mainframe DevOps
• Create, update, and maintain existing mainframe code, and analyze and resolve common errors
• Apply modern approaches to the mainframe, including microservices, APIs, cloud, and AI and machine learning
• Work with datasets and databases and put together effective reports
• Understand how to work with modern cloud systems, like AWS, for pursuing data migration