The mainframe one is unique, mostly because the web ways (full of web governance, web 2.0, social media, and open source) don’t compare to thing like COBOL, a 50 year old language that still accounts for 80% of the currently active computer code (i.e. 250 billion lines of it) worldwide.
That's where APM (Application Portfolio Management) comes in. we must apply such management technique to understand whether we are in balance, or whether our applications will go the way of COBOL with that sudden threat to their existence and a need for immediate reaction.
According to NASA's Office of the Chief Information Officer :
"[APM] is really about implementing a repeatable process to assess what we have, and, if an application is not performing or does not meet our architectural requirements, eliminating it and replacing it with a better performing application. We're doing it to try and reduce the money we spend on maintaining existing applications (that don't perform well) and freeing up that money to invest in new and better performing applications."