Hi ,
This is only available on ASA 9.3.2 and above:-
http://www.cisco.com/c/en/us/td/docs/security/asa/asa93/configuration/general/asa-general-cli/interface-zones.html#pgfId-1068427
Also , using the Active/Active HA on the ASA to load balance is nothing but distributing your traffic into two different failover groups and keeping the groups active on one ASA and the other group active on the other ASA device.
http://www.cisco.com/c/en/us/support/docs/security/pix-500-series-security-appliances/99131-multiple-context.html
http://www.cisco.com/c/en/us/td/docs/security/asa/asa82/configuration/guide/config/ha_active_active.html
Thanks and Regards,
Vibhor Amrodia