How to get parent site lists

im using javascript on a subsite to retrieve items list which is on the parent site when i use this

var clientContext = SP.ClientContext.get_current();
var lists = clientContext.get_site().get_rootWeb().get_lists();
var oList = clientContext.get_web().get_lists().getByTitle(listName);

a message on subsite home says this list is not exist on this site