Storing Cooked Food Hot I have been looking for an answer for the following question everywhere, but could not get hold of any answers.

The question is "At what temperature can I store (keep for serving) cooked meals in its Hot state, and for how long. 
Note that the meal portion that I would like to store is for one person (Airlines like meal), the meals should be store in oven like warmer".

Many sources says that meals should be kept at a temperature higher than 60 degrees C, but it never states for how long can I keep it and it does not mention the portion size. As I guess big portions are different from a single portion meals.

I would really appreciate it if you could provide references.
First of all there's portion size: that should not matter. I'm assuming here that you transfer the food from cooking straight into the oven to keep warm, and not re-heating after cold storage. This means that your food will integrally cool down to the ambient temperature in your oven.
For temperatures there are lots of resources available, such as Fact sheet or Governmental guidelines. The first link provides the only real reference to timing I could find. It seems like from a food safety point of view there is no clearly defined maximum storage period, as long as you keep the food out of the &quot;Danger Zone&quot;. Regular stirring of the food and the right temperature apparently keep it safe for long enough for the authors of these resources to think it not worth mentioning.
There is how ever always taste and texture to consider. I would not recommend keeping any dish warm for many hours, regardless of the temperature.