Corporate restructuring makes everything a flux, so you might as well revisit some core fundamental questions. Here's how to do this professionally:
Start floating your CV now. Line up interviews in competing companies. Attend to them. Score a job offer, and have it put into writing, with exact salary, which should be at least 10%++ of your current one.
Take a clear empty page, and write on top: "Business value provided". Put down your major contributions, and achievements. Wherever possible, put the company's expected dollar value near to it. For bonus points, sum it up on the bottom, and minus your current salary. Difference is "Profit provided directly to the company's bottom line".
Float this to your manager's desk. At this position, you have only one fundamental question to your boss: "match or pass?" :)
A corporate spin-off is a good time to do this: 1, to ensure, that your position will not be made redundant; 2, if it is, you have a backup plan.
If the parent company's "getting rid of you", however, there are even more fundamental questions you might want to ask yourself: is this really a profitable division, or merely a loss leader? Does this company have a future, and the adequate growing options for you, personally?
To answer these questions, you must have an opportunity cost estimation; and for that, you must have second (and preferably, third) options -hence, the strategy above.
To conclude, the best time to do your job research is every other month; and the best time to ask for a raise is always now :)