Accessing more than 2.0 GB of memory on HP-UX

 

This section describes necessary settings to get access to more than 2.0 GB of memory on HP-UX within a V5 process.

Background

By default, Version 5 processes on HP-UX can allocate up to approximately 1.9 GB of memory for storing data. The 4 GB address space offered by the operating system being split into 4 quadrants of 1 GB each; most of first 2 quadrants are reserved for private data allocations, most of last 2 quadrants are  reserved for shared objects. It is possible to increase  the default data allocation capabilities up to approximately 3.0 GB (1 GB remains for shared objects). Such capability requires additional settings in order to be effective :

Operating System settings

Version 5 required customizations

Since R14 the V5 main executables are already flagged to enable the use of the third quadrant. One can disable it by using the chatr command ( this operation requires root authority on default installation) :

One can go back to initial behavior by restoring the original copy or enabling the use of the third quadrant :