[plt-scheme] current-library-collection-paths in Embeded MzScheme

Hi all,

In C program that embeds MzScheme, by default I can't require any standard PLT library.
The reason seems to be that (current-library-collection-paths) is empty. The further
reanson seems to be that (find-library-collection-paths) or (find-system-path 'addon-dir)
returns empty.

Although I can first manually set (current-library-collection-paths) and then require,
will it be better that this is don't automatically?

I also wonder why (current-directory) is also empty in Embeded MzScheme.

Thanks.

Sincerely,  
Chongkai Zhu