In my understanding, the GAMCA centres are located only in certain countries like (India, Bangladesh and PAK etc). If you are a resident of Malaysia (immigration of GCC may ask for your valid resident permit if you are applying from a country other than your home country), you can get the test done from any medical centre (Pantai/mediviron clinics etc) and need to get the NONGAMCA form filled by a medical officer. It depends on which country you are heading to. You can find the sample of NON GAMCA form for Bahrain (https://lmra.bh/portal/en/announcement/show/133).
Please check the requirements from your employer and they are a better person to guide you.
@Gopinath Rajaram, Any centre in JB, can issue the certificate ( Pantai or Mediviron clinics). Use the format shared by employer to obtain the certificate