COBOL
COBOL (Common Business-Oriented Language) is one of the oldest programming languages still in active use, designed in 1959 for business, financial, and administrative data processing on mainframe systems.
18 resources across 3 libraries
Glossary Terms(2)
COBOL
COBOL (Common Business-Oriented Language) is one of the oldest programming languages still in active use, designed in 1959 for business, financial, and adminis…
Fortran
Fortran (Formula Translation) is one of the oldest high-level programming languages, created in 1957 for numerical and scientific computing, and it remains in…
Study Notes(15)
CICS Fundamentals for COBOL
Learn how CICS (Customer Information Control System) lets COBOL programs run as online, transaction-based applications, using pseudo-conversational design, EXE…
COBOL and DB2
Learn how COBOL programs embed SQL to interact with a DB2 relational database, using host variables, cursors, and SQLCA/SQLCODE for error checking.
COBOL Best Practices
Practical conventions for writing maintainable, defensive, and performant COBOL that survives decades of maintenance by different teams.
COBOL in Mainframe Systems Today
How COBOL continues to power core banking, insurance, and government systems on IBM z/OS mainframes, and why it remains business-critical in 2026.
COBOL Interview Questions
The core language, file-handling, and mainframe concepts most frequently asked in COBOL developer interviews, with the reasoning behind each answer.
COBOL Program Structure
How a COBOL source file is organized into divisions, sections, paragraphs, and sentences, plus the classic fixed-format column layout.
COBOL Quick Reference
A condensed cheat sheet covering program structure, PICTURE clauses, common verbs, and file I/O syntax for day-to-day COBOL development.
Conditional Logic in COBOL
Master COBOL's IF/ELSE, nested conditions, the EVALUATE statement, and condition-names (88-levels) for expressing readable business rules.
Error Handling in COBOL
Learn how COBOL programs detect and respond to runtime errors using FILE STATUS codes, the ON SIZE ERROR and ON OVERFLOW phrases, and structured exception hand…
Loops in COBOL
See how COBOL's PERFORM statement is used in practice to build counting loops, nested loops, sentinel-controlled read loops, and how to exit them safely.
Migrating Legacy COBOL Applications
A practical look at the strategies, risks, and techniques organizations use to modernize decades-old COBOL systems without disrupting business operations.
Setting Up a COBOL Environment
How to install a free COBOL compiler like GnuCOBOL, choose an editor, and prepare your machine to write and run COBOL programs locally.
SORT and MERGE in COBOL
Learn how COBOL's built-in SORT and MERGE verbs reorder and combine files using the language's native sort work file mechanism.
What Is COBOL?
An introduction to COBOL, the business-oriented programming language that still powers banking, insurance, and government systems worldwide.
Your First COBOL Program
Write, compile, and run a complete Hello World COBOL program, and learn the most common mistakes beginners make along the way.