1. A computer-implemented method for storing multiple applications in single sectors of mobile device memory namespaces, comprising: storing, for each application stored in a mobile device memory namespace, an application directory entry in a data memory block of an application directory in the mobile device memory namespace, each application directory entry comprising: an application identifier (AID) for each corresponding software application stored in one or more data memory blocks of a sector of the mobile device memory namespace; a starting memory block number for a starting memory block in the sector of the mobile device memory namespace, wherein the starting memory block holds at least a part of a corresponding software application; and a size for the corresponding software application, the size defining a number of contiguous data memory blocks including the starting data memory block that store the entire corresponding software application.