Locking has been updated in 7.1. You are able to use Default Locking or Optimistic Locking. In addition, there are things that will affect the locking of a case. Such as a child case, when opened will have the same locking setting as its parent. However if it is instantiated it can use a different type of locking from the parent.
Locking still proves a good issue to be discussed in pega 7.
You need to decide the type of locking mechanism requirement by your application.
For ex- There is a case where only one person is allowed to work at a time then we will opt for default locking, on the other hand,our application requires the users to work parallely on single case then we opt for Optimistic locking.