If it's standard thickness oak boards it should not be glued as J-John explains. However there are a few timber systems that are becoming popular which are similar to a laminate, or engineered boards. Some of these are glued to create a floating floor or overlay system. They need to be laid on to a suitable underlay or in some cases a floor paper They are only glued to each other and not to the subfloor. Like other timber floors it is important to leave an expansion gap around the whole perimeter.
If it is a traditional Oak floor then the boards should be laid on to battens over the concrete and either screwed or nailed. It may also be necessary to ensure that the fixings are suitable to fix to the concrete subfloor if it is important to limit the thicknes of the battens. Occassionaly it may be necessary to lay directly to concrete this is less desirable and will require a suitable dampproof membrane to be used as an underlay.