The duo's current deals are due to expire at the end of the ongoing campaign.
However, McCoist is eager not to lose two of his most "valuable" players to the Bosman ruling.
"There has nothing been planned yet but it goes without saying that they are players who are very valuable to the team and the club," he told the club's official website.
"I would imagine in the next couple of months or so that their representatives will be sitting down with the club to discuss extensions to their contracts.
"Hopefully from their point of view and from our point of view we can do some good business."
McCulloch has been with Rangers for five years, while goalkeeper Alexander joined in 2008.