Company is being acquired, what should I expect?

I am an account executive for a SaaS company that is being acquired by one of the big software companies (Salesforce, SAP, Oracle, sized companies) and I was looking for a little insight.

I have worked at the current company for around a year and a half, and that was my first job coming out of college, so I don't have much experience with this situation. Any input would be greatly appreciated.

1. What is it like to work in a huge software company of that size, my current one is under 1000 employees, it's not exactly a mom and pop company. But I would love to know more about the day to day of the companies like Oracle, SAP, Salesforce size.

2. Obviously job security is a top concern, I have never been in an acquisition before, and I don't know what to expect. I am relatively confident in my position, I started out as an SDR moved into an AE role after 8 months and was continuously given more responsibility. But there might be some overlap within the product I sell and theirs. I went ahead and update my resume and started looking just in case, but I would prefer to stay where I am.

3. Also I just don't know what to expect as far as being acquired and assimilating into a new software company. I know it's common in the software industry so I was hoping someone would have some experience, even if it is anecdotal.

Thanks so much