Managing data structures in a plurality of memory devices that are indicated to demote after initialization of the data structures

Provided are computer program product, system, and method for managing data structures in a plurality of memory devices that are indicated to demote after initialization of the data structures. Indication is made to data structures to demote after initialization from a first level memory device to a second level memory device. The first level memory device has lower latency than the second level memory device. In response to completing initialization of the data structures in the first level memory device, the data structures indicated to demote after initialization are copied from the first level memory device to the second level memory device and removing the data structures indicate to move after initialization from the first level memory device.