outBuffer = (LPTSTR) LocalAlloc( LPTR, sizeof(TCHAR) * MAXSTRINGLENGTH );

static extern IntPtr LocalAlloc(uint uFlags, UIntPtr uBytes);

The following method wraps LocalAlloc in order to allocate a zeroed memory block of the specified size:

    IntPtr memPtr = LocalAlloc(LocalMemoryFlags.LPTR, new UIntPtr((uint)size));

LocalAlloc

These flags may be used with the LocalAlloc function.

See the [LocalAlloc] function on MSDN.