Hi sd wasim,
This link is definitely going to answer all your questions about ipv6 on your ASAv:
Can I pass traffic for both IPv4 and IPv6 on the same interface, at the same time?
Yes. You must simply enable IPv6 on the interface and assign both an IPv4 and an IPv6 address to the interface, and it handles both types of traffic simultaneously.
http://www.cisco.com/c/en/us/support/docs/security/adaptive-security-appliance-asa-software/119012-configure-asa-00.html
Hope this info helps!!
Rate if helps you!!
-JP-