can anyone give me an advise to get a good introduction of terms of zOS, ISPF, MVS, TSO and so on. I have some experience on linux, so i try to map my knowledge onto the given terms. But I believe, there are many differences. For example how can I imagine the filesystem of zOS. If I talk about qualifiers in ISPF, does that means pathes? And what about Dsorg ( PO,PS ), Recfm ( FB, VB, VA ), Lrecl and Blksz. I'm searching for a good introduction, perhaps first architecture of zOS ( does there exist a kernel or something else ) and how coherenc the other term ( MVS, TSO ).