Abstract: Methods and apparatus for software threads to access both shared and unshared data in a single software unit. Prior to a thread executing a set of computer language instructions in a collection of software units, it creates a copy of the respective location data segment of the collection of software units. Thereafter, prior to the thread accessing a software unit in the collection of software units that has an associated set of shared data, the thread sets a pointer in its location data segment copy to the equivalent value in the location data segment of the collection of software units. The thread will thereafter access the set of data associated with the software unit when it executes the respective software unit. Also, prior to the thread accessing a software unit in the collection of software units that has an associated set of unshared data, the thread creates a copy of the set of unshared data.