Unless you are running on some non-standard OSPF implementation, ospf makes no use of AS in the fashion that BGP uses AS. RFC 2328 and RFC 2740 makes no mention of OSPF as an EGP but specifies how OSPF works within an autonomous system.
What are the problems occurs, while configure Ospf using AS number rather than Process ID.
Is there is any defualt AS number of OSPF like AD 110.
Just like it was stated OSFP doesn't use a AS number it's a Process ID number but for some reason Cisco calls it a AS number. The Process id is only used on the local router to keep track of that instance of OSPF thats running.