JSON.stringify results in stackoverflow only when the fields added to the dictionary(which is tried to be coverted to json string using stringify) are of type objects.  

// say the input json event which is taken in the task logic is having a string field nfName, for e.g. "nfName": "pnf300"

var nfName = executor.inFields.get("nfName")  //typeof nfName is object here

var obj = {};
obj["nf-name"] = nfName
JSON.stringify(obj), this is causing stackoverflow.

Changing to obj["nf-name"] =String(nfName) solves the issue.
 
So, if key/value getting assigned is of type object, casting them to String is the workaround to fix this bug with Rhino, as shown below.

obj[String(key)] = String(value)
 
Need further analysis on this, or track this existing bug in Rhino