Memory Resident Only Cookies?

I am trying to beef-up the security when passing data between pages. I am currently using the following code to navigate between some of my pages.

<a href="javascript: GetFormValue(FRMTRANSFERS.TXTHOSPITALID,'ADDPATIEN T');">
<SCRIPT LANGUAGE="JavaScript">
function GetFormValue(FField,StrPage)
{
var myField = FField
var myNumber = myField.value
self.location = StrPage + ".asp?ID=" + myNumber;
}
</SCRIPT>

I would rather use cookies to do this but i need to know if you can create a cookie that doesn't get written to the harddrive. I can't use session variables as i can't write then in Javascript - at least i think not -