Incidentally, In addition to what is stated here about the use of the ^JRNDUMP utility, there is also a very useful entry point, SELECT^JRNDUMP, which takes up to 7 arguments, so you can filter results in many ways to suit your needs. This can be helpful in trying to see the exact cause of journal growth. 

For complete documentation, go here:

http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...