Examples of the code assigning values to the link:
In this case the variable strHeader_LineIds carries a string over 20k characters.
Example of what I'm actually seeing in client side:
I guess this issue may have something to do with the browser's URL limit? I am using IE and I learned IE has a maximum URL length limit as 2,083 characters from Here. But how can the link show up with 5,239 characters?
Then again just reading your post could be a limit issue.
Have you tried assigning the long to an element in the background and then referencing that as part of the javacript. I know IE gets funny with spaces in passed in parameters.