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Glossary

This is a specicially curated glossary designed to help beginners understand key mainframe terms through simple explanations and relatable analogies.

Term Explanation Think of it like...
z/OS Operating system for IBM mainframes Windows/MacOS
DB2 (Database 2) Database management system for storing structured data SQL/ Excel
CICS (Customer Information Control System) Processes online transactions for users and applications Web Server
JCL (Job Control Language) Script language which tells z/OS which jobs to run Workflow/ Batch script
3270 Terminal Text-based interface used to access the mainframe Command Prompt/ Terminal
z16/ z17 Latest generations of IBM mainframes with AI and high security Server/ Mainframe System
SMF Logs (System Management Facility) System logs recording events and performance data Flight recorder/ Analytics
RACF (Resource Access Control Facility) Security system that manages user access and permissions Login manager/ Admin controls
REXX (Restructured Extended Executor) Simple scripting language for automation on z/OS Python/ PowerShell
Sysplex (System Complex) Multiple mainframes linked to share workloads Server cluster
COBOL (Common Business Oriented Language) Programming language for business and financial systems Pseudocode - but it actually works
IPL (Initial Program Load) Starts up the mainframe and loads z/OS Booting a computer