Further Reading: CICS Fundamentals

IBM Official Documentation

CICS TS for z/OS Application Programming Guide (SC34-7381) — The primary reference for CICS application development. Covers command-level programming, pseudo-conversational design, BMS, file access, and program control in depth.
CICS TS for z/OS Application Programming Reference (SC34-7382) — Complete syntax reference for all EXEC CICS commands. Essential desk reference for CICS developers.
CICS TS for z/OS BMS Macro Reference — Detailed reference for all DFHMSD, DFHMDI, and DFHMDF options. Covers advanced features like cursor positioning, dynamic attribute modification, and partition support.
CICS TS for z/OS Problem Determination Guide (SC34-7383) — Debugging techniques, trace analysis, and common error patterns. Invaluable when things go wrong in production.

Lowe, Doug. Murach's CICS for the COBOL Programmer. Mike Murach & Associates. — Widely regarded as the best tutorial for learning CICS programming. Clear explanations with many complete program examples. Highly recommended as a companion to this chapter.
Horswill, Matthew. CICS: A Practical Guide to System Fine Tuning. — For those interested in CICS performance and tuning. Covers task management, storage management, and DB2 integration.
Sayles, Jonathan. CICS Transaction Server from Start to Finish. IBM Press. — Comprehensive coverage from basic concepts to advanced topics including web services and event processing.

CICS and Liberty: What You Need to Know (SG24-8418) — How to deploy Java applications alongside COBOL in CICS using the Liberty JVM server. Essential reading for modernization projects.
CICS Transaction Server: Building RESTful Applications — How to expose existing CICS COBOL programs as REST APIs with JSON payloads.
Architecting for the Modern CICS Transaction Server (SG24-8520) — Architecture patterns for integrating CICS with cloud-native applications, containers, and microservices.

IBM Z Xplore (https://www.ibm.com/z/resources/zxplore) — Free cloud access to z/OS including CICS. Work through hands-on CICS programming exercises without installing anything.
IBM CICS Developer Center — Tutorials, code samples, and community resources for CICS development.
CICS TS Liberty Profile Starter — A simplified CICS environment for development and learning, available as a Docker container.

Chapter 28: Advanced DB2 Programming — DB2 skills are essential for most CICS programs, as online transactions frequently access DB2 data.
Chapter 30: Advanced CICS Programming — Builds on this chapter with TSQ/TDQ, multi-screen transactions, browse/scroll patterns, and channel/container programming.
Chapter 31: IMS DB Concepts — Some CICS environments use IMS DB instead of (or in addition to) DB2.
Chapter 37: Testing Strategies — Covers CICS-specific testing techniques including CEDF (the CICS Execution Diagnostic Facility) and automated transaction testing.