My understanding of the RPI3 is that it contains 1GB of RAM and that the memory can not be upgraded / added to (ref: https://www.raspberrypi.org/forums/viewtopic.php?f=45&t=114326 )
After analysing the partitions that CentOS creates during the installation process / writing the image to a SD card, I noticed that the CentOS image creates a swap partition that is only 512M in size.
I am now wondering if, increasing the size of the swap partition (using either SUSE Yast partitioning tools, Gparted or some other partition tool that supports both Linux based file system formats and that can resize these partitions) to 2.5 GB (ie. increasing the swap partition to be no larger then 1.5 times the size of the actual physical RAM) and then increasing the 'swappiness' be changing vm.swappiness variable within /etc/sysctl.conf could resolve the memory limitations of the RPI3.
Obviously, using the above method would slow down read/write access to the RAM (as the RPI3 is now using a SD medium to act as virtual memory, which is slower then actual physical RAM), but theoretically, this should give the RPI3 an increase the RAM of up to an extra 2.5GB (resulting in 3.5GB of accessible RAM).