How to use stacks

[eja]

I found this in the help file.

Note: You can make new stacks only when viewing a single folder and not when viewing catalog folders recursively.

Well, I am in the File System Mode and when I try to implement stacks all of the options are greyed out except roll/unroll stack. Perhaps I am trying to view the folders recursively but I"m not sure exactly what that means. I can get the feature to work in the Catalog mode.