An operating system permits sharing of a sub-process (or process unit) across multiple processes (or tasks). Each shared sub-process has its own context. The sharing is enabled by tracking when a process invokes a sub-process. When a process invokes a sub-process, the process is designated as a parent process of the child sub-process. The invoked sub-process may require use of process level variable data. To enable storage of the process level variable data for each calling process, the variable data is stored in memory using a base address and a fixed offset. Although the based address may vary from process to process, the fixed offset remains the same across processes.