If you have twists in the line stretching it will not help much. One way this can happen with a line fresh out of the box is if you took apart the line spool and pulled the line coils off and cranked them on to the reel you will have one twist for every coil. You can check this by pulling 3 or 4 feet of line off the reel and form a loop. If the loop twist up then you have twists in the line. You will then need to carefully work the twists out by laying out the line and repeatedly pulling the line through your fingers until all the twists are removed.

If you do not have twists then Ducksterman's advice will take care of the problem.