EWLC: the entry tier where one batch run sets the whole bill.

EWLC stands for Entry Workload License Charges, the entry tier of IBM's Workload License Charges (WLC) family. It is a Monthly License Charge (MLC) metric, so it bills recurringly every month rather than as a one time charge, and it is sub-capacity, so the charge tracks measured consumption rather than the full rated capacity of the machine. It applies to the smaller z/OS machines, historically the lower capacity business class models, where the larger Variable Workload License Charges (VWLC) tier did not fit.

The mechanic is the same one that governs the rest of the WLC family: each month the Sub-Capacity Reporting Tool (SCRT) measures the Rolling 4-Hour Average (R4HA) of utilization for each eligible product, and you are billed against that peak. A product peak can never exceed the z/OS peak. To stay eligible you must run in 64-bit z/Architecture mode and submit the monthly sub-capacity report to IBM.

On an entry machine the Rolling 4-Hour Average is volatile because the box is small: a single batch window, a heavy report run, or a month end cycle can lift the four hour average well above the daytime online baseline. The bill is set by the single highest R4HA point in the month. The table below shows how one overnight batch peak resets the billable MSU figure for a representative 50 MSU entry box.

The estate runs near 28 MSU most of the day, yet the bill is struck at 47 MSU because of one overnight batch peak, and that 47 MSU figure caps the billable peak for every sub-capacity product on the machine. On a small box the gap between the daily baseline and the single monthly peak is the whole game. Figures illustrate the mechanic, not any published rate.

AEWLC is the advanced successor to EWLC, the entry counterpart to the VWLC to AWLC move on larger machines. The advanced metrics carry the technology dividend of the newer hardware, so the per MSU schedule differs even though the sub-capacity mechanic is identical. The common buyer mistake is staying on a legacy entry metric after a hardware refresh that entitles you to the advanced schedule.

The pressure point on entry machines is the sensitivity of the R4HA. Because the box is small, the distance between the online baseline and the single monthly peak is proportionally large, and one mistimed workload can lift the bill for every product. That same sensitivity is the opportunity: small, deliberate moves to the peak produce outsized savings.