legato reference link for Secure storage, by default app’s maximum secure storage is also 8192 bytes and it is configurable using maxSecureStorageBytes in “xdef” file.
And for each secure storage items can have maximum size of 8192 bytes.
My query is,
what is “xdef” file ?
Where it is present?
whether maximum size for each item configurable ?
The xdef is meant for sdef and adef files (there is no xdef files).
So yes it is actually possible to set it from an adef file, as you can see from the doc: Application Definition .adef - Legato Docs