I started my career with a first job in 2009 (not long time ago!) as a COBOL/JCL programmer (and went on to do TELON programming later) for one of the biggest r

I started my career with a first job in 2009 (not long time ago!) as a COBOL/JCL programmer (and went on to do TELON programming later) for one of the biggest retailer in the country. The systems that managed the forecasting for replenishable and non-replinshable products, markdowns (i.e., discounts) on products in the stores, stock warehouse etc. across the country was completely built on COBOL/JCL+DB2 stack combined with TELON online screens for business to manage the solution/system. This system practically worked round the clock with hardly any downtime, and in the peak season (like Christmas when the sales/transactions were at it's high) too worked without any major issues. I'm sure IBM still earns a big chunk of revenue from mainframes from these big customers. I remember an attempt was made to migrate some (if not all) to a new generation data analytics platform and it didn't go very well, so they just stuck with what they had. One of the main reason I can think of is the the cost of this migration was too high (vs. the realised benefit) as the system just worked for the business and was quite resilient. I since then jumped ship to the very technology they were trying to migrate too and have never looked back really. I think I can still work my way out of COBOL/JCL + TELON/CICS, perhaps I will forget them very soon :)