Before any workstation is opened or activated, GKS itself must be opened. This must be the first call in any GKS program as it performs the initialization. The last call should be to close (exit from) GKS.
CALL GOPKS(ERRFIL, BUF) ....... CALL GCLKSERRFIL defines the FORTRAN logical unit number to which all error messages will be sent. BUF is the amount of memory space to be used. (This parameter is ignored by the GKSGRAL and GKSGRAL-3D implementations.)