the ezsys("querystring") result will be cached in the compiled template, which causes always the same parameters to be used as long as that compiled file is used. when a cache clean is issued, the compiled template renews and again the same values will be stored until the next cache clear.

to test, put this code in pagelayout, outside any cache-block:

<h1>captured params:

</h1>
the timestamp:

reload the site with:
www.site.com/?some=thing
www.site.com/?other=thing
www.site.com/?your=ownValues

the timestamp changes (proof that a proper reload was done), but the params will always be the ones in the first call, until the template caches are cleared.