If your application only needs immediate sending (CONFIG_APP_STORAGE_INITIAL_THRESHOLD=1), the following prj.conf excerpt minimizes RAM usage for the storage module.
# Minimal storage configuration
CONFIG_APP_STORAGE=y
CONFIG_APP_STORAGE_BACKEND_RAM=y
# Keep only a single slot per type (no buffering planned)
CONFIG_APP_STORAGE_MAX_RECORDS_PER_TYPE=1
# Send a message for every sample
CONFIG_APP_STORAGE_INITIAL_THRESHOLD=1
# Drop development features
CONFIG_APP_STORAGE_SHELL=n
CONFIG_APP_STORAGE_SHELL_STATS=n
Note
For the RAM backend, the actual RAM consumed by the ring buffers scales with which data types are enabled and the value of the CONFIG_APP_STORAGE_MAX_RECORDS_PER_TYPE Kconfig option.