After many hours of travel, and some sleep I have for you - this link with the basis information: https://www-01.ibm.com/support/knowledgecenter/ssw_aix_71/com.ibm.aix.genprogc/lrg_prg_support.htm
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Mainly, it depends on how much memory you have in the system, aka partition or virtual machine. note also 0x80000000 is not the maximum (hope i am getting all the zeros right). From memory, it is...