In support of Philippe’s comments…..
In a really enjoyable past life, to meet “Six Sigma” belt requirements, we did “tuning” projects. This for all of GE’s DBDC environments, CICS, DB2, IDMS & etc, and their associated products.
This was a “speed and profitability” analysis. AKA “do it faster and lower CPU”.
We examined and analyzed every IDMS user setting, including the famed “Bob Dobbs zaps”, with actual production work loads.
The result for IDMS multitasking and I quote “Recommendation: Turn off multitasking. Unless the region is , It is unlikely that the region requires multiple TCBs to get the requested work done. The IDMS multitasking option can cause the region to consume 20% more CPU to manage the additional TCBs.”
No region at GE benefited from multitasking.
When I arrived here multitasking was turned on. I exercised the sigma project here. End result was multitasking was turned off, while implementing other “speed and profitability” recommendations. The average reductions were 37% CPU and 20% response.
I sure do miss my former GE “CDAC” peers, Ron Lamb, Dan Hall, Brian Schroeder, Doug Jolley, Jack Koebbe, George Cable, Gerry Irwin and Dave Burton.