Where COBOL Runs Today

By day, users on 3270 terminals, web, and mobile apps call online COBOL transactions in CICS or IMS (often through z/OS Connect REST APIs).

2.1 Industries

Typical COBOL workloads core ledgers, deposits, loans, card authorization and settlement, end-of-day batch, interest calculation policy administration, premium rating, claims processing, actuarial batch tax processing, social security and unemployment benefits, motor vehicle records, payroll Retail & logistics inventory, pricing, order processing, warehouse management Airlines, travel, healthcare reservations back-ends, fare calculation, claims adjudication, billing

2.2 Platforms

IBM Z mainframes (z14, z15, z16, z17) running z/OS — the dominant home of COBOL, alongside CICS, IMS, Db2, VSAM, and JCL batch. Also IBM i (ILE COBOL).

Linux, Windows, Unix — GnuCOBOL, Rocket (formerly Micro Focus) Visual COBOL / Enterprise Developer, IBM COBOL for Linux on x86, IBM COBOL for AIX; Visual COBOL can also target the JVM and .NET.

Cloud — rehosted COBOL on AWS, Azure, Google Cloud using Rocket Enterprise Server or similar runtimes; AWS Mainframe Modernization offers managed refactor and replatform paths.

2.3 A typical mainframe application

By day, users on 3270 terminals, web, and mobile apps call online COBOL transactions in CICS or IMS (often through z/OS Connect REST APIs). By night, a scheduler runs batch JCL job streams of COBOL programs, sorts, reports, and extracts. Both work against the same Db2 tables, VSAM files, and IMS databases.