> and have large-scale mission-critical batch processes that run on them, where the core function is relatively consistent over time.
I think most mainframe applications involve OLTP not just batch processing – commonly a hybrid of both. e.g. around a decade ago I did some work for a large bank which used CSC/DXC/Luxsoft Hogan as their core banking system – that's a COBOL application that runs under IBM CICS for transaction processing, although I'm sure it had some batch jobs in it too.
(I myself didn't touch any of the mainframe stuff, I was actually helping the project to migrate some of its functions to a Java-based solution that ran on Linux – no idea what its current status of it all is a decade on.)
I think most mainframe applications involve OLTP not just batch processing – commonly a hybrid of both. e.g. around a decade ago I did some work for a large bank which used CSC/DXC/Luxsoft Hogan as their core banking system – that's a COBOL application that runs under IBM CICS for transaction processing, although I'm sure it had some batch jobs in it too.
(I myself didn't touch any of the mainframe stuff, I was actually helping the project to migrate some of its functions to a Java-based solution that ran on Linux – no idea what its current status of it all is a decade on.)