update cookie from webmethod (PageMethod) using ajax

I have one requirement  where I want to update cookie from a webmethod. The webmethod is called from ajax using PageMethods.

Here is how my .aspx page looks like

In code behind

[webmethod]
public static void updateCookie(string arg1)
{

//some code to update cookie

}

 

in javascript I call the method using ajax

PageMethods.updateCookie(arg1, OnSuccess, OnError, OnTimeout)

but this does not updates cookie. Is their any way to update cookie from webmethod?
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