how big can be the string sent back to the server with the following code?

Question

Hello i need to send some data back to the server and i want to use the following code.

Does someone know if there is a limit on the dimension of the string sent with the following code

  $(document).ready(function() {
          $.ajax({
              type: "POST",
              url: "test.aspx/PassBackdata",
              contentType: "application/json; charset=utf-8",
              data: "{'args': '" + Ldata + "'}",
                   dataType: "json",
                   success: AjaxSucceeded,
                   error: AjaxFailed
               });
           });
           function AjaxSucceeded(result) {
               alert(result.d);
           }
           function AjaxFailed(result) {
               alert(result.status + ' ' + result.statusText);
           }  
 

      };