Dallas-based Comerica is kicking in 50-thousand dollars to help keep a couple of Oak Cliff libraries open. Comerica’s donation will be funnelled through Friends of the Dallas Public Library and is designated for the two branches thought to be most in need of help. With that in mind, the money will help the North Oak Cliff and the Polk-Wisdom branches in a period when Dallas has been drastically cutting funding for library staffers and materials. The proposed 2011 budget provides for reduced hours at the central Dallas library along with about 120 layoffs, system-wide.