DOCUMENT:Q123730  02-NOV-1999  [fortran]
TITLE   :BUG: R6000 After Many Calls to RunQQ If Linked with Defaults
PRODUCT :Microsoft Fortran Compiler
PROD/VER::1.0,1.0a
OPER/SYS:
KEYWORDS:

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0, 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 the
default options of FL32, it does not have the problem described above.

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

NOTE: It is not necessary to apply BINDMSF to the TASK.EXE because it is being
run from TEST.EXE, which will have already loaded the MS-DOS extender. Feel free
to use BINDMSF on TASK.EXE; it will have no effect on this test.

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

SAMPLE CODE task.for
--------------------

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

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

Additional query words: nofpsnt 1.00 1.00a docerr

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword3 kbFORTRANPower100DOS kbFORTRANPower100aDOS
Version           : :1.0,1.0a

=============================================================================

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