Can somebody please explain
Why anyone would choose to run Linux on such an unspeakably overpriced hardware / host platform which has such a small available skills base to support it?
Is it still the quaint idea that reliability and availability comes from Jurassic park scale overkill in hardware resilience and that somehow if you pray hard enough you will never have a failure?
In the existing mainframe victims, erm , customers, I can see why the mainframe priests would want to run something else on their expensive white elephant to preserve their jobs by ensuring that you can't run a basic Linux without being inducted into the company of white coats. This doesn't hold for new customers though, unless their CIO is ex-mainframe shop and doesn't want to start paying for his own golf club membership at this point in his career.
"Cheap" in the context of mainframe is like "truth" in the context of politicians, a purely relative term that has little relation to the generally accepted meaning.
Perhaps I just underestimate how good the IBM sales people are, maybe they stopped selling snow to Eskimos and Oil to Gulf fishermen because it was too easy, now they make their real sport convincing people that a mainframe can be cheaper than something else? Maybe it is cheaper to run your Linux on a mainframe than develop a new stealth bomber but that is about it...