使用GzipStream时，如何确定缓冲区的大小？

I'm trying to decompress a GZipStream. The problem is that the "Length" property on the stream throws a "NotSupported" exception. How do I know what size to make my buffer when I'm reading the bytes from the stream? Since it's compressed I don't know how large the uncompressed version will be. Any suggestions?I'm trying to decompress a GZipStream. The prob