Mountable integrated circuit package system with intra-stack encapsulation

A mountable integrated circuit package system comprising: mounting a first integrated circuit device over a package carrier; mounting an interposer including a central aperture over the package carrier, an intra-stack interconnect connected between the interposer and the package carrier, and the first integrated circuit device within the central aperture; and forming an intra-stack encapsulation over the package carrier and surrounding the interposer.