DOCUMENT:Q196606 13-JUN-2001 [sna] TITLE :APPC DLL Has A Hardcoded Limit of 4 KB GDS Data Size PRODUCT :Microsoft SNA Server PROD/VER:WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft SNA Server, versions 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1 ------------------------------------------------------------------------------- SUMMARY ======= The IBM host will reject General Data Stream (GDS) data that is larger than the 4 KB increments hardcoded in the Appc.dll file. MORE INFORMATION ================ The application writes the data message and indicates the length of the data, but the APPC .dll file formats the message into LU 6.2 data format. The data flow should be similar to the following: - The CPIC application calls CMSEND, passes a pointer to the data, and sets the send length to 8872. - The CPIC .dll file calls the MC_SEND_DATA function, passes a pointer to the data, and sets the send length to 8872. - The APPC .dll file formats the RU with the Logical Length size and GDS header information (to indicate LU 6.2 application data) and includes the application data (following IBM LU 6.2 data formatting specifications): 9000 12FF 9000 02B0 The Logical Length fields (9000, 9000, 02B0) and GDS ID (12FF) account for 8 additional bytes, making the full data sent equal to 8880 bytes. The data is split into the RU size, and segmented within the maximum frame size (265 bytes on this Synchronous Data Link Control (SDLC) connection). The host stack does not recognize the continuation bit, therefore, any data larger than 4 KB that is sent, is rejected. The APPC .dll file is hardcoded to send application GDS data sizes of 4 KB. REFERENCES ========== IBM SNA Format and Protocol Reference Manual: Architectural Logic for LU Type 6.2 (IBM #SC30-3269), Chapter 2: GDS Variables. Additional query words: ====================================================================== Keywords : Technology : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ211 kbSNAServ400 kbSNAServ211SP1 kbSNAServ211SP2 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ300SP2 Version : WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1 Issue type : kbinfo Solution Type : kbnofix ============================================================================= 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. Copyright Microsoft Corporation 2001.