getstore stores the file exactly as it was provided. If it's text, and if you want convert the character encoding to what you use locally (i.e. decoding using the current encoding, then encoding using the desired encoding), it's up to you to do so.

If the document in question is an HTML document, the encoding should appear in the Content-Type HTTP header. It might also appear in a META http-equiv element inside the document. If you convert the encoding, don't forget to adjust the META element.