some circumtances i must use global variable.

read :
http://msdn.microsoft.com/en-us/library/aa891830.aspx

more example how to use :

SysGlobalCache globalCache;
globalCache = ClassFactory.globalCache();
globalCache.set(strFmt("%1%2",curUserId(),"WhatEver"), 0, "ANY VALUE");

on other class.

SysGlobalCache globalCache;
globalCache = ClassFactory.globalCache();
info(strFmt("%1",globalCache.get(strFmt("%1%2",curUserId(),"WhatEver"), 0)));