Checking Control 
In checking control, you can define for each order type and checking rule which type of check is to be used for the material availability check:
No automatic check when an order is created, released or partially released (see Checking Rule )
ATP check
Check against planning
Check when an order is saved
You can also assign checking rules for production resources and tools, and for capacities or define that no check is to take place.
You define checking control in Customizing for
Shop Floor Control
by choosing
Operations
Availability Check
Define Checking Control
.