Does OS continue the execution even after closing from Postman?

Yesterday, I was testing fairly complex application, and it did send wrong data while I watching the logs in IIS so when I caught it, I straightly closed IIS server and the Postman request. 

Then, I wanted to re-try with new data set, and started IIS server again, sent request to OS API using Postman. I saw that IIS process both canceled data and new data. 

Does that means OS continue execution even after closing Postman request? 

What I see here is OS seems retry the requests until my server IIS respond. 

I can't think exact cause.