It’s not possible to unzip files natively on the iSeries, however there is a version of PKZIP for the iSeries that will allow you unzip files on the iSeries.
The simplest answer is usually to review the <a href=”http://publib.boulder.ibm.com/infocenter/iseries/v5r4/index.jsp?topic=/rzaha/jar.htm”>Java jar tool</a>. Note the link on that page to Sun’s documentation. Also note the reference to the <a href=”http://publib.boulder.ibm.com/infocenter/iseries/v5r4/index.jsp?topic=/rzaha/javatool.htm”>Java ajar tool</a>.
There may be particular requirements such as transferring files in binary mode, passwords on the .zip file, etc., that the creator of the file will have to help with.
PKZip/Unzip is available as a commercial and supported product. Web site is noted above.