#### 5.3.1 Limiting chunk usage

You can limit Polipo's usage of chunk memory by setting `chunkHighMark` and `chunkLowMark`.

The value `chunkHighMark` is the absolute maximum number of bytes of allocated chunk memory. When this value is reached, Polipo will try to purge objects from its in-memory cache; if that fails to free memory, Polipo will start dropping connections. This value defaults to 24MB or one quarter of the machine's physical memory, whichever is less.

When chunk usage falls back below `chunkLowMark`, Polipo will stop discarding in-memory objects. The value `chunkCriticalMark`, which should be somewhere between `chunkLowMark` and `chunkHighMark`, specifies the value above which Polipo will make heroic efforts to free memory, including punching holes in the middle of instances, but without dropping connections.

Unless set explicitly, both `chunkLowMark` and `chunkCriticalMark` are computed automatically from `chunkHighMark`.