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# LU memoization
The least-used memoization strategy (sometimes called "Least Frequently Used") is a [variant of LRU](./LRU.md) that evicts items that are used least frequently once its threshold has been exceeded.
> In simple terms, the LU cache will remove the element in the cache that has been accessed the least, regardless of time.
## General use
To create a core.memoize LU-backed memoized function use the `clojure.core.memoize/lu` function with an optional seed map or a `:lu/threshold` parameter:
(memo/lu function <seed> <:lu/threshold number>)
Example code is as follows:
```clojure
(ns your.lib
(:require [clojure.core.memoize :as memo]))
(def memoized-fun
(memo/lu identity {} :lu/threshold 3))
```
The default `:lu/threshold` value is 32 and refers to the number of elements in the cache required before the LU logic is applied.
Please read the [clojure.core.cache information regarding LU caches](https://github.com/clojure/core.cache/wiki/LU) for more detailed information, use cases and usage patterns.
As always, you should measure your system's characteristics to determine the best eviction strategy for your purposes.
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