Arduino SoftwarSerial

Arduino SoftwarSerial

I have pin 2 and 3 used as my serial input from a gps module. I have everything set up working correctly, however, I want to perform more tasks than just reading a gps module.
  void setup() {
    Serial.begin(9600);
    ///////////////////////////////////
    // 9600 NMEA is the default baud rate
    mySerial.begin(9600);
    Serial.println("NMEA Sentences");
    // uncomment this line to turn on only the "minimum recommended" data for high update rates!
    mySerial.println(PMTK_SET_NMEA_OUTPUT_RMCONLY);

    // uncomment this line to turn on all the available data - for 9600 baud you'll want 1 Hz rate
  //    mySerial.println(PMTK_SET_NMEA_OUTPUT_ALLDATA);

    // Set the update rate
    // 1 Hz update rate
    mySerial.println(PMTK_SET_NMEA_UPDATE_1HZ);
    // 5 Hz update rate- for 9600 baud you'll have to set the output to RMC only (see above)
    //   mySerial.println(PMTK_SET_NMEA_UPDATE_5HZ);
    // 10 Hz update rate - for 9600 baud you'll have to set the output to RMC only (see above)
    //  mySerial.println(PMTK_SET_NMEA_UPDATE_10HZ);
    //////////////////////////////////

  }
Assuming I have all the setup etc correct in my code which I do, if I have this
void loop() {
  if(mySerial.available()) {
     Serial.print((char)mySerial.read());
  }
}
and the NMEA sentence displays just fine. However I want to perform more tasks, and so I need to perform something like this
void loop() {
  // perform lots of other functions here
  while(!otherFunctionsComplete) ... // Very time consuming code
  // just want to read 1 full nmea sentence from gps
  getGPSData();

}
void getGPSData() {
  // wait here until i get the GPRMCA sentence

  while (mySerial.available()) {
      Serial.print((char)mySerial.read());
    }
}
The problem is I only get the buffer size 64 bytes of data using the second method. I want to wait and read the incoming bytes on the serial until i get a '$GPRMCA' and then store all the rest of the bytes. Any help with this?