Developing and Porting C and C++ Applications on AIX

3.2. The 32-bit user process model

This section provides a brief explanation about 32-bit user process models. Every 32-bit user process has its own address space, whose maximum size is 4 GB. An address space is prepared by the kernel as part of the process initialization tasks as a subset of virtual memory address on the system. A 32-bit address space is composed of up to sixteen 256 MB memory chunks called segments. Each segment has a specific purpose illustrated in several figures in the following sections. A segment is divided into smaller size memory chunks called pages. A page is an atomic unit, with which the virtual memory manager (VMM) in the kernel uses to satisfy many different memory requests.

On AIX, the default page size is 4 KB, ...