Does anyone know something about MVS and JCL?
Is it possible to explain to me what MVS is? And what JCL is used for?
I believe you are referring to MVS and JCL.
MVS is the operating system for the IBM mainframe systems and JCL is the job control language for the mainframe. You could correlate MVS to Linux and JCL to Bash for example.
The AS/400 / iSeries / IBM i / i5 is considered a midrange machine. It's operating system is called OS/400 or more recently i5/OS.