Is OCSG threadsafe / Weblogic web service thread safe

hi,
can advice if OCSG threadsafe / Weblogic web service thread safe?
We had implemented the following communication service where ReplaceContentService_Service is the weblogic web service client object.. Was wondering if it is thread safe as we had tried similar implementation in axis, it is not.

private static ReplaceContentService_Service arService = null;

private ContentInformation getContentWS( GetContentRequest getContentRequest, String appInstId ) throws Exception

{

                  if (arService == null)

                  {

                        arService = new ReplaceContentService_Service_Impl();

                  }

                  arPortType = arService.getReplaceContentServiceSoapPort( username.getBytes(), password.getBytes() );

                  credProviders.add( new ClientUNTCredentialProvider( username.getBytes(), password.getBytes() ) );

                  theStub = (Stub)arPortType;

                  theStub._setProperty( "weblogic.wsee.transport.connection.timeout", Integer.parseInt( timeout ) );

                  theStub._setProperty( Stub.ENDPOINT_ADDRESS_PROPERTY, endpoint );