You need to replicate this configuration change to all servers, then recycle all servers affected. The parameter "Cluster_Name_Cache_Size=100" NOTES.INI parameter value will allow more than the default of 40 clusters by setting a new limit of 100 clusters.
Supporting Information:
No hard limit has been discovered for Cluster_Name_Cache_Size, so administrators will need to raise the value and monitor performance as they would for any other cache limit. As a general rule, set the parameter no higher than needed to hold all of the clusters defined in the environment.