menchar -
Unfortunately, there is no way to tell the CVI linker to enforce 16 byte alignment, and there is no way to use someone else's linker from within the CVI environment. You've demonstrated some of the limitations this strict enforcement, and while it is unlikely there will be a change for this in the near term, it is something that the development team will investigate.
The base address of the application - as I think you know - simply determines where the image is laid down in the process' virtual address space. As you've guessed, this can greatly affect the size of the contiguous memory block you can allocate. However, not only does the base address of your executable change the theoretical size of the largest contiguous block you can allocate, but all dll's you are dependent upon change this as well. Once they've been mapped into the virtual address space (which you have less control over because relocations are more probable) the largest contiguous block is further limited.
The default setting in CVI is to load the executable with a base address at the 4MB logical memory location. This is primarily convention, because back in the days of Win 95 the space below 4MB was reserved by the OS. Now, because of this convention, other dll's, including OS dll's, avoid this address so that relocation of your executable should not be necessary. While it is rare that an exe would need to be relocated, the sacrifice of 4MB is probably worth it to maintain the convention, as well as a relatively high level of control over where your executable is loaded.
NickB
National Instruments
