> Do you have a z series in your garage to hack around with?

You just need a Linux PC with the IBM Z Development & Test Environment.

(Of course, ZD&T, even the “Personal Edition”, doesn’t exactly have hobbyist-friendly pricing.[0])

You can do cheaper (i.e., free) with Hercules, but only with older OS’s.

[0] https://www.ibm.com/products/z-development-test-environment/...