Thank You Andy.
Well the first command actually solved my problem.
request_body_max_size 1024 KB.
It actually limit the upload size of file.But not in every uploader site such as sendspace,wetransfer etc.I was checking in these sites by uploading large file, but it was invain.But the I checked in http://www.freeuploadsite.com/
site by uploading files and its
100% working.I can limit uploading in squid config and check in the above mentioned site whether its working or not perfectly.
Since I am new to linux,I was not properly guided
. Any ways now I will try to limit uploading for other sites like Sendspace, WeTransfer which gave me so much headache..Thank You all.