After rebuilding my zabbix_agentd for 64bit on AIX (see ZBX-6564), I've now unearthed another issue:

In AIX 6.1, the key "system.stat[memory,avm]" (active virtual pages) only works if zabbix_agentd is compiled as 32bit. If the agent is compiled as 64bit, this key becomes "not supported".

On AIX 5.3 this problem doesn't happen.

As an additional note, is there a reason why I can't test "system.stat" keys on the command line? This command returns
ZBX_NOTSUPPORTED:

   /usr/local/sbin/zabbix_agentd -c /usr/local/etc/zabbix_agentd.conf -t 'system.stat[memory,avm]'

But this one also returns ZBX_NOTSUPPORTED although the agent seems to be reporting values to the server just fine:

  /usr/local/sbin/zabbix_agentd -c /usr/local/etc/zabbix_agentd.conf -t 'system.stat[memory,fre]'

Perhaps I'm doing something wrong here, or this is reason for another bug report...