How to fix ‘unimplemented or unreasonable conversion requested’ error in JSON?

I am trying to pass a large number of records as a stringify object from client to the server. In the server side there is a function called ‘Get_Records’ to capture that string object. Then it should parse the string object into records back and do necessary modifications. This is the way of calling the stringify function from client side.

stringify(rec, "IS_TRANSACTION=${IsTransaction}^COMPANY_ID=${CompanyId}^PR_TRANSACTION_SEQ=${PrTransactionSeq}^SPRICE=${SPrice}^SQUANTITY=${SQuantity}^", JSON) into SelectionVar;

call Get_Records(SelectionVar) into invoiceExist;

Below is the server side function to capture the string object.

FUNCTION Get_Records(
   selection_string_  IN VARCHAR2 )  RETURN VARCHAR2
IS 
   records_               json_array := 
   json_array.parse(selection_string_);
   current_selection_     VARCHAR2(32000);
BEGIN
   //Code
END;

But when I try to pass the string object for a large number of records from the stringify() function, it is not captured by the server side function ‘Get_Records’. It gives an error called, ‘unimplemented or unreasonable conversion requested, details: undefined undefined’. I tried using the ‘CLOB’ datatype for the server side function. But it is also not working for a very large number of records. Is there a proper way to pass the string object retrieved from the stringify function to the server side. ?