You can change the max file size allowed in the preference menu. It is limited to 1GB when running the 32-bit version of Spike.
There are several ways you could reduce file size depending on your needs, you can increase RBW, add a sweep interval, or take advantage of the decimation in time/freq on the recording toolbar.
If you need even more flexibility than what Spike provides, you could consider programming to the API directly, then you full control over the acquisition and recording process.
Regards
