Below, straight out of the PDGA rules manual should answer all questions. Yeah, I know it boring but it is the straight answer.
A. When the disc is released, a player must:
(1) Have at least one supporting point that is in contact with the playing surface on the line
of play and within 30 centimeters directly behind the marker disc (except as specified in
803.04 E); and,
(2) have no supporting point contact with the marker disc or any object closer to the hole
than the rear edge of the marker disc; and,
(3) have all of his or her supporting points in-bounds.
B. Stepping past the marker disc is permitted after the disc is released, except when
putting within 10 meters.
C. Any throw from within 10 meters or less, as measured from the rear of the marker disc
to the base of the hole, is considered a putt. A follow-through after a putt that causes the
thrower to make any supporting point contact closer to the hole than the rear edge of the
marker disc constitutes a falling putt and is considered a stance violation . The player must demonstrate full
control of balance before advancing toward the hole.
D. A player must choose the stance that will result in the least movement of any part of any
obstacle that is a permanent or integral part of the course.
E. If a large solid obstacle prevents a player from taking a legal stance within 30 centimeters
directly behind the marker disc, the player shall take his or her stance immediately
behind that obstacle on the line of play. The player must comply with all the provisions of
803.04 A other than being within 30 centimeters directly behind the marker disc.