Dice Holdings Inc.’s board of directors has authorized as much as $65 million in additional stock buybacks, according to Dow Jones Newswires. The company owns Urbandale-based Dice.com, a professional career website. The new authorization takes effect once Dice completes a $30 million repurchase plan unveiled last August. Dice Holdings said it has repurchased about $29.4 million shares as of March 7 under that program. The company reported that its fourth-quarter earnings soared 82 percent as revenues climbed 25 percent. The company’s stock price is down 36 percent in the past year.