The DB2 12 catalog – what happened since DB2 11 – by Steen Rasmussen

There are many ways to learn about a new DB2 version, but using the catalog is probably the fastest and most enlightening. Once you look at the revision track in the DB2 Catalog and Directory section of the SQL Reference Guide, study the column changes, additions as well as new catalog tables, you have a very good overview of everything worth to know about that specific DB2 version