If Catalog Service is going down frequently but coming up if restarted, it may be the case its going down due to Ingestion/Hbase/Solr connectivity issue. I would suggest to raise technical case with Informatica support and attach LDM.log so that support can assist you on this.
Thanks for your reply Shailesh. Its not only with CS but mostly all services configured on nodes goes down.
Already raised case with IGS and they suggested its server side issue as I updated in my earliest post.