# Domain

> Use an allocation associated with the lifetime of a domain.

## Definition

* **Type:** Field
* **Namespace:** [Unity.Collections](/engine/6000.6/script-reference/unity/collections.md)
* **Assembly:** UnityEngine.CoreModule

```csharp
Domain = 6
```

### Remarks

You don't need to free this memory, because Unity frees it automatically at domain unload. However, to conserve memory, you can free it at any time. Freeing a large number of such allocations in one frame, such that the array of freed pointers is larger than L2 cache, might exhibit a measurable loss of performance.

**Note**: The Domain allocator can track a maximum of 262144 (256 \* 1024) individual allocations. If the number of allocations exceeds that number, Unity logs an error and does not free excessive allocations automatically.