Mainframe, MVS and zOS Discussion

Hello,

I was reading the evolution of z/OS from its primitive MVS OS and coming from Windows world, I need to ask, why is the data set name is restricted to only 44 characters? And why, for Tape Drive, label is of 17 characters and not more, at least 44 characters?

Hopefully, I don't bother too much.

You first must understand that data set names go back to 1964 when the first 360 was announced. Back then, 44 characters was considered adequate and a good compromise between longer names for readability and shorter names for faster system processing.

Tape data set names are 17 characters because that is all the space available in the tape label header and that again goes back to System 360.

Rather than asking why, you would be far better off just learning -- and accepting -- the limitations as they exist. Unless you are a historian, the "why" does not matter since you cannot change the 44-character limit anyway.

Thanks Robert.

I agree with your view, however, coming from windows-world makes you curious about such things.

It's probably not coincidental that 44 characters give you five octets separated by periods. You also need to bear in mind the limitations of the original JCL input media - 80 column punch cards.

however, coming from windows-world makes you curious about such things.

There should be no consideration/compsarison why things are different in the 2 environments. There are Very Few similarities between these environmants.

IBM invites 44 finalists to the inaugural Master the Mainframe World Championship http://www-03.ibm.com/press/us/en/press ... /43308.wss. Surely that's not a coincidence.

So, did they mean "44 'Characters' of Championship" ...