There is a version of DB2 for mainframe, but it’s a totally different codebase as I understand it. The operating system on a mainframe provides a lot of what mo

There is a version of DB2 for mainframe, but it’s a totally different codebase as I understand it. The operating system on a mainframe provides a lot of what modern app developers get from their database and caching systems, generally with better fault tolerance and availability. So if you have an app built for mainframe, it often will not have an external database dependency. Doing transactions can just look like writing to memory or files.