There Lot of scenario's where you need to store the some configuration information accross the cluster.
WebSphere Distributed MAP (Dynacache) is the way to store some information accross the different web application but it still doesn't satisfies your requirement when your production is multi cluster environment . Because each cluster will create separate Dyna cache (distributed map) objects. Only way to share in this case either manually update the each cluster by having some servlet or jsp that access dyna cache and update (but it may not be proper solution).
Solution for this problem is using the Data Replication Service and enable the data replication service for the Dyna cache instance (just like the way you enable the session replication service)
we can define another replication domain that will have only Distributed MAP objects(dynacache instances). It would be very small amount of memory compared to session replication .
• Login to the WebSphere Administrative console for your server.
• Go to Resources > Cache Instances > Object cache instances .
• Click the Browse Clusters button and choose the cluster that you want to create the cache for.
• Click Apply to save your choices.
• Click New to create a new cache.
• Enter missedabspath in the Name field and services/cache/iwk/missed in the JNDI name field. These values are used to lookup the cache and use it. Leave all other fields set to their default values.
• Select Enable Cache Replication.
• Go to the Full group replication domain drop-down box and select the name of the cluster you want to cache.
• Select Choose Push-Only from the Replication type drop down box.
• Enter 1 in the Push Frequency field. Leave all other fields set to their default values.
• Click OK and then Save > Save > OK
For the complete information, follow below article explains a way to define different replication domains for the dyna cache and session