I have just upgraded my N4 to Kitkat and tested some of old apps being developed using IBM Worklight. It was shocking for me that JSON Store stopped working
In addition to Amit Kumar's answer, it should be noted that a fix will be released in the near future for Worklight 5.0.6.x and 6.0.0.x as well as the upcoming 6.1.0, where the feature compatibility is restored.
JSONStore, a Worklight feature that enables persistent storage of JSON documents, is not working as one of the third-party libraries supporting this feature is using an API that is no longer available.
Here is LINK to read more.