Is it possible to store large size files in server root folder?

Please see my comment to the question: not clear what's not working. Of course, you can store large files in that folder, unless it does not fill up all the available disk space and blocks essential system functionality.
 
I can only speculate that the problem is not in storing those files, but in downloading them by the client size of any other related HTTP server functionality. Again, there is not enough information from you, but you should know your HTTP server settings. Naturally, there is a number of limitations, such as maximum file size for different kinds of operations, maximum time allowed to processing of HTML request, etc. Usually, all such things are configurable. Address to the documentation of the server, whatever it is.
 

—SA