Thank you. Indeed, it works all fine. The first time, I forgot to check the "ramdisk" checkbox.
A cosmetic problem: The shadow to the folder on the ramdisk is broken, of couse, because I create the folder in a cmd file located in the startup folder. So I have to use a config.sys command:
c:\os2\cmd.exe /c createfolders.cmd (is this correct?)
(haven't tried yet.) But how can I be sure that the ramdisk is generated before executing the cmd file?