KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q32743: _fmalloc and halloc Run-Time Library Update

Article: Q32743
Product(s): See article
Version(s): 5.10   | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | appnote softlib buglist5.10 c51lib.arc | mspl13_c
Last Modified: 14-JUN-1990

The following is an application note describing the _fmalloc and
halloc allocation limit of 4 megabytes.

Note: This information applies to the standard run-time libraries such
as SLIBCE.LIB, MLIBC7.LIB, etc. This information is not applicable to
the LLIBCMT.LIB, LLIBCDLL.LIB, or CRTLIB. The 4 megabyte limit remains
embedded in these libraries.
The _fmalloc (which is equivalent to malloc in large and compact
models) run-time library functions that were released with Version
5.10 of the Microsoft C Optimizing Compiler impose an arbitrary limit
of 4 megabyte as the amount of memory you can allocate in OS/2. In
addition, the halloc run-time library routine impose a single
allocation limit of 4 megabyte on memory requests.

The files described below can be used to replace existing modules
in your libraries in order to overcome these limits. The new limit for
_fmalloc is 16 megabytes, while the new limit on single allocations
with halloc is a function of the operating system, i.e., you can
allocate as much memory as OS/2 allows.

To update your libraries, copy all of the files listed below from
the Software Library into the same directory as your libraries. Make
sure that the library manager LIB.EXE also is in the current directory
or in your PATH. You then can run the file LIBFIX.CMD to update your
libraries. If you are running in DOS or in the DOS Compatibility Box
in OS/2, you can run the LIBFIX.BAT batch file.

Note that LIBFIX.CMD and LIBFIX.BAT assume that your protect-mode
combined libraries use the default naming convention, i.e., the
protect-mode combined library names are of the form where X is the
memory model (S,M,C,L) and Y is the floating point option (E,A,7), as
follows:

   XLIBCYP.LIB

For example, LIBFIX will attempt to update the file SLIBCEP.LIB,
the small-model emulator library for protect mode. If your protect-mode
combined libraries are not of the form given above, it will be
necessary for you to update your libraries manually or else modify the
.BAT or .CMD file so that the proper libraries are updated. A sample
command line to the library manager is as follows:

   lib -+halloc.s -+crt0.s slibcep.lib ;

This command line will update the small-model protect-mode combined
library. If your protect-mode library has a different name (e.g.
slibce.lib), you would use the following command line:

   lib -+halloc.s -+crt0.s slibce.lib ;

It is not necessary to update the real-mode combined libraries because
the fix to the libraries does not affect programs that use the real-mode
libraries.

Please note that the library manager will create a backup of each
library that it updates. Once you are satisfied that the update
procedure is completed successfully, you can delete the files with the
.BAK extension.

Below is a description of the files included with this application
note. These files can be found in the Software Library by searching
for the filename C51LIB, the Q number of this article or S12001.
C51LIB was archived using the PKware file-conversion utility.

   halloc.txt   This file

The following are replacement modules to correct the limit on
halloc:

        halloc.s    halloc.obj for small model libraries
        halloc.m    halloc.obj for medium model libraries
        halloc.c    halloc.obj for compact model libraries
        halloc.l    halloc.obj for large model libraries including
                               multi-thread and dynamic link libraries

The following are replacement modules to correct the limit on
_fmalloc:

        crt0.s      crt0.obj for small model libraries
        crt0.m      crt0.obj for medium model libraries
        crt0.c      crt0.obj for compact model libraries
        crt0.l      crt0.obj for large model libraries
        crt0.mt     crt0.obj for multi-thread support library LLIBMT.LIB
        crt0.cdl    crt0.obj for multi-thread DLL library CDLLOBJS.LIB
        csu.dll     crt0.obj for single thread DLL library LLIBCDLL.LIB

If you are using _fmalloc and you require more than 16 megabytes of
memory, you can edit the file BRKCTL.INC, which is included with the
startup source code. Change the value MAXSEG_PM in this file and then
rebuild the appropriate modules as outlined in the README.DOC that is
included in the startup code directory. This value was originally 64;
the CRT0.OBJ modules on this disk were assembled with the value of
MAXSEG_PM set to 256.

If the start-up code is not on your hard disk, you will need to go
through the C Version 5.10 setup procedure again and choose the option
to copy the start-up code to your hard disk.

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.