Put your sensitive variable in RAM

// declare variable
byte[] requestParameterBuffer;
// allocate it in RAM , ensure the memory length
requestParameterBuffer = JCSystem.makeTransientByteArray(
(short) (queryString.length() * 2), JCSystem.CLEAR_ON_RESET);

JCSystem reset / clean memoryOptions :

• JCSystem.CLEAR_ON_DESELECT
• JCSystem.CLEAR_ON_RESET