For some unknown reason when I first started writing mainframe JCL articles I ended up writing quite a few about Generation Data Groups of which this one was the first.
What is a GDG?

Not all of the new pages on the site are web related. Here’s one where I answer a question regarding GDGs on mainframe computers.
With a Generation Data Group you have both the individual datasets as well as the catalog that groups them together. The purge and force keywords determine whether one, the other, or both [...]