Size of chunks in ToChunk methods?

Is the chunk created by: 
chunk = HTLoadAnchorToChunk(anchor, request);
The size of the file being requested?
Is there any way to grab the requested file by lines or by buffer?
I have looked at the source and it looks like you malloc the whole file into memory?!
Could this be a problem with big files (100's of megs)?

--Dave Horner