Learn COBOL with Real Code Examples

Programs divided into IDENTIFICATION, ENVIRONMENT, DATA, and PROCEDURE divisions

Strong emphasis on record-based data structures

Runs primarily on mainframes (IBM z/OS) or COBOL compilers on modern OSes

Sequential and indexed file models

Batch execution via JCL workflows on mainframes

COBOL source code

Compiled into machine code or bytecode

Executed on mainframes or local OS

Batch jobs handle large datasets

Screen/terminal I/O via DISPLAY/ACCEPT

Batch-driven processing

Modular sections and paragraphs

Copybook-based data reuse

Record-oriented data handling

Mainframe transaction workflows (CICS)

Core banking systems

Insurance claim engines

Government benefit systems

Payment processing pipelines

Enterprise mainframe workloads

Self-documenting English-like syntax

Structured business-oriented logic

Strong emphasis on data integrity

Batch-oriented workflows

Long-term maintainability

Run batch jobs in parallel partitions

Optimize file access patterns

Modularize business logic

Leverage mainframe parallelism

Use Load modules efficiently

Refactor COBOL to microservices via wrappers

Convert datasets to relational DBs

Rewrite modules in modern languages if feasible

Preserve business logic during modernization

Migrate batch jobs to cloud schedulers