You can make use of the linker files and have a shared/common region between bootloader and application to store the data as required.
This PSOC6 example gives a sample linker files, that you can adapt to your requirements as required. https://www.cypress.com/documentation/code-examples/ce220960-psoc-6-mcu-ble-upgradable-stack-bootloader
linker concept would remain same across both platforms.
Hope it helps.