Why should I use a Collection rather than a standard AS/400 Library for my data?

Joe Sam Shirah

A collection provides a logical grouping of SQL objects...[and] consists of a library, a journal, a journal receiver, a catalog, and optionally, a data dictionary. See: CREATE COLLECTION for the SQL command.

By creating a collection, all of the objects needed for SQL functionality, including Commit and Rollback are available. Otherwise you can only use autocommit mode or create your own journals and receivers.

Note that, with some restrictions if you created a data dictionary, you can create a Collection, then move files/tables to it from your old library.