BUG: R6000 After Many Calls to RunQQ If Linked with Defaults

• Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0 and 1.0a

SYMPTOMS

RunQQ fails and returns error R6000 (stack overflow) after being called many times. The failure occurs after less than 100 calls (the exact number depends on things like system memory) given the following conditions:

• Stack checking is turned on when compiling the task called from RunQQ.
• The application was linked using the default stack size of 1MB 'reserve' and 4K 'commit'.
• The application is run from MS-DOS.

RESOLUTION

Set the linker stack option to 32K 'reserve' and 4K 'commit'. This is the default when compiling and linking using FL32 on the command line.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

This problem does not occur with FORTRAN PowerStation 32.

MORE INFORMATION

Page 168 of the User's Guide states that the default stack for the linker is 1MB 'reserve' and 4K 'commit'. It also states that this is 0x1000000 and 0x4000 respectively - which is inconsitent, it is actually 0x100000 (1MB) and 0x1000 (4K). These are the values used by default in the Visual Workbench. Applications built this way will fail as described above.

The default stack used when building from the command line with FL32 is 32K

'reserve' and 4K 'commit'. When an application is compiled and linked using

To demonstrate the problem, build both sample programs using the linker's default options in the Visual Workbench. The only compile option required is /Ge for TASK.FOR. Then exit Windows and run TEST.EXE from MS-DOS.

To demonstrate the problem without using the Visual Workbench, use the following commands (assuming the maintenance release is installed). The linker version for the maintenance release is 1.0F.

   FL32 /c /Ge test.for task.for
   LINK test.obj libf.lib libc.lib
   BINDMSF test.exe
   LINK task.obj libf.lib libc.lib

Sample Code TEST.FOR

C Compile options required: none or /Ge (it will not affect the test)

      include 'flib.fi'
      include 'flib.fd'

      character*1 answer
      integer*4 i
      integer*4 r

      do i=1,100

          write(*,*)"ready to runqq task.exe"
          r = runqq("task.exe","/none")
          if (r .ne. 0) then
              write(*,*)i," task.exe failed"
              read(*,FMT='(a1)') answer
          else
              write(*,*)i," task.exe was successful"
          end if

      end do

      end

C Compile options required: /Ge (must turn on stack checking for TASK)

      write(*,*)"control passed to task.exe"
      end