Our mainframe runs Linux. It really loses its luster when that happens.
Our company provides conversion from mainframe to Linux. I wrote the mandatory file locking module for our batch job launcher. I also wrote a generation file manager.
We recently completed a migration for a French government agency. Their software had been split between IBM MVS and Bull HN GCOS 8 on about 6 different platforms. Back in the 1990's the mainframes had been distributed in various cities around France. We migrated them to VM's running Red Hat Linux.
If it’s an IBM, it can run on an IFL.
I still say zLinux isn't real Linux ....