Modules in Mainframe

1) JCL - Job Control Language

2) COBOL - Common Business Oriented Language

3) VSAM - Virtual Storage Access method

4) CICS - Customer Information Control System

5) DB2 - Database

6) IMS DB/DC - Information Management System Database/Data Capture


File Database in Mainframes :Data is stored in mainframe either in files, DB2 database or IMS database. DB2 database and IMS database we will cover later.

There are below types of files in mainframes : ( In mainframes files are called as datasets)
1) PS - Sequential dataset ( these are like notepad files or word files as we have in personal computers)
2) PDS - Partitioned datasets ( These are like folders which will differnet files in that folder, But inside PDS files there will be just PS files, we call it as members. ) 
3) VSAM files -
There are four types of VSAM files -
a) ESDS
b) KSDS
c) RRDS
d) LDS   

4) GDG files : These files generally used for bkup purposes. In production environment there willl be daily, weekly, monthly, quaterly, annualy running jobs in order to take bkup we use GDGs.