Limit of CDT variable in process model

Hi Experts

I have a problem where I need to generate an excel without storing the data in DB.

I'm using Export CDT to excel smart service,

But I have nearly 6000 rows to fetch with only 3 columns(Request ID, DOC ID, Doc Name).

I want to know what is the maximum amount of data in terms of size(MB or KB) a process variable of type CDT can hold.

And if is there any better solution of what I'm doing, please suggest me.

Thank you in advance