There is AS400 opening at my area. It is still good to start career in this kind of job?

Not here, but maybe in Malaysia

@SortOfTested Yeah Iam at Malaysia. My bad, I have edited my post.

@aryzor
As a generality:

It's a technology that has far outlived it's lifespan. I don't think it has a strong future in general. It all depends on whether or not organizations can afford to replace them.

@SortOfTested
Why outlived?
Systemi is still alive and kicking.
Quite a lot of DB heavy business (Eg, accounting, warehousing, logistics) applications still run on it, because of the absurdly high performance of DB2.

I could provide a litany of counterexamples to that in businesses I've worked with, but I won't derail.

What I will point to is IBM's cratering hardware business. The only division making profit is Redhat, and even their GS division is contracting at an ever increasing rate. At this rate, HCL will own their hardware business in a decade.

Consider it very legacy.

No-one is using it *new*, and many are outright replacing it. It's still prolific enough that there's going to be some work in it for years to come, but that level of work is only going to decrease.

Because of that, there's often some rather highly paid jobs available, as it's not something anyone really wants to learn.

If I were a bit closer to retirement age, then I'd maybe take a job like that for 5 years or so as I wouldn't need to worry about my long term career. But I definitely wouldn't if I was just starting out.