How to get querystring value in stateless form?

How to get querystring value in stateless form?

I have written a custom function to show a stateless form.

  1.     querystring = "";
  2.     for each Account in Accountinfo
  3.     {
  4.         querystring = (querystring + "accid=" + (Account.ID)) + "&";
  5.     }
  6.     openUrl("#Form:Send_SMS?" + querystring, "Popup window", "height=400,width=400");

The forms opens correctly. But I am not able to access the query string passed in the form.

  1. l = input.accid;
It throws error accid is undefined.

What am I missing: