GDG - Generation Data Group in z/OS mainframe system

Generation Data groups or GDG's are a group of data sets which are related to each other chronologically and functionally.

These related Data sets share a unique Data set name.

Every GDG data set has a Generation number and version number assigned to each data set.

Example:

'MYLIB.LIB.TEST.G0001V00'
'MYLIB.LIB.TEST.G0002V00'
'MYLIB.LIB.TEST.G0003V00'

Creation of GDG

Before using GDG, we need to create GDG index and model. IDCAMS utility is used to create GDG index.

Creating Model

Once the index has been created, a model data set must be created. This model data set contains specifications for the DCB subparameters for all data sets that will belong to that GDG.