What is LOCK escalation?
The Lock escalation is the process of converting of the low level locks (such as row locks, page locks) into the higher level locks (such as table locks). Each lock is a memory structure too many locks would mean, more memory being occupied by locks. To prevent this from happening, the SQL Server escalates the many fine-grain locks to the fewer coarse-grain locks. The Lock escalation threshold was definable in the SQL Server 6.5, but from the SQL Server 7.0 onwards it is dynamically managed by the SQL Server.