Version 12.6.0 was released in December 2013. You can find the documentation of IBM ILOG CPLEX Optimization Studio in the Information Center. Start with the Release Notes to learn about new features and changes. Downloads are available via the Passport Advantage or Academic Initiative sites.
A fix pack, to be installed on top of an existing 12.6.0 installation, is now available at IBM Fix Central. The fix pack contains fixes, libraries compatible with Visual Studio 2013 for the CPLEX Optimizers, including CP Optimizer, and the ability to use the distributed parallel MIP algorithm from OPL. More info at https://ibm.biz/BdFFGC. Fix list: https://ibm.biz/BdFFnq