xlcOpen() Function Should Not Be Used in Function Macro (95890)

SUMMARY

The xlcOpen() function should not be used in a dynamic-link library (DLL) function registered as a function macro. This function requires approximately 11,800 bytes of stack space to operate. Rarely will this much space be available on the Microsoft Excel stack when a DLL function registered as a function macro is called.

The exact amount of stack space required to open a file varies with the type of file. Worksheets containing embedded charts require more stack space than other files. If xlcOpen() is called with insufficient stack space, the result usually is a general protection (GP) fault in Microsoft Excel.

MORE INFORMATION

The following implementation methods are recommended in cases where xlcOpen() functionality is required:

Use the macro function OPEN instead. Use a macro to open files as needed, then call the necessary DLL functions. Note that calling a macro function containing OPEN from a DLL won't work properly, because this requires more stack space than calling xlcOpen() alone.
Use xlcOpen() in a DLL function registered as a command macro. DLL functions registered as command macros (Macro_type 2) have approximately 1000 bytes less stack overhead. Consequently, top-level command macro DLL functions generally have enough free stack space to call xlcOpen().

If xlcOpen() must be used, always call xlStack first to check stack space:

      #define STACKMIN_XLCOPEN 11800

      Excel4(xlStack,&xlResult,0);

      if (xlStack.val.w < STACKMIN_XLCOPEN)
         {
         ErrorHandler();
         }
      else
         {
         Excel4(xlcOpen,&xlResult,(LPXLOPER) xlFile);
         }