How to limit height expand and show vertical scrollbar?

How to limit height expand and show vertical scrollbar?

I am trying to control a textbox. Here's my initial code:

  1.  $(document).ready(function () {
  2.             $('.expanding').autogrow();          
  3.         });
  4.         $(function () {
  5.             $("textarea[id$=txtInsertDefinition]").blur(function () {
  6.                 $(this).next().hide("normal");
  7.             });
  8.             $("textarea[id$=txtInsertDefinition]").focus(function () {
  9.                 $(this).next().show("normal");
  10.             });
  11.         });
I want to limit the autogrow height, to say 100px, and then turn on vertical scroll bar for this textbox. How do I do that?