mount f f:\games\VOC\ -freesize 500MB
--> creates the path f:\blabla with enough free space for the full installation (full install is more than the initial 105 MB free disc space in DosBox)

mount e e:\ -t cdrom -usecd 0 -ioctl
e is my cdrom drive, where the gamedisc is in. This command line helps to make it work as an 'older' cdrom drive. Even though this might not be necessary the error is also given when I only use
mount e e:\

creates the path f:\blabla

Nope.
Re-read exactly what Qbix posted.

Do as Qbix and wd says. If you doubt their advise, look their titles. Your title is Newbie, their title is DOSBox Author. Guess which one knows most about DOSBox.

We could also just keep it as a misunderstanding;)

I thought Qbix quoted my input because he wanted explanation for it, since I did not see that he had changed anything in what I wrote. I do now so I'll give it another try. No attack at the the 'DosBox authors' from this 'newbie'.

Nice of you to tell me that they know more of DosBox than me though.

You don't wanna see it if MiniMax is NOT nice. But mostly he is nice as you noted.

If changing the mounting letter does not work, try reinstall the game.

allright that definatly cleared the xtoath.mss error.

Next during the installation I get an error code with lots of red text containing

-------------------------------------------------------------
DOS/4GW error (2002): transfer stack overflow on interrupt at 08h at 80:000006FD
TFS32: prev_tsf32 4FC0
----------------------------------------------------------

Then 6 lines with this form:
CS= 80, USE16, byte granular, limit B94F, base 14C370, acc 9A
All containing different values

and at the bottom
---------------------------------------------------------
Error: The file 'STRTGAME.TMP' could't be opened
---------------------------------------------------------

Could this have to do with unreadability of the disc?

And again, thanks for all replies, I appreciate you take the time for it.

It could be a problem with the CD, but there could be other causes as well. Somewhere here in these forum there is a link to a replacement for this DOS/4GW thingy that is part of your game. For some games, this replacement (called DOS32A) works better than DOS/4GW. Search for DOS32A, and see if you can figure out how to run the game with that instead.

Links:
http://dos32a.narechk.net/index_en.html, http://dos32a.narechk.net/manual/index.html