The general mindset is "if you need high integrity, you probably also need to statically determine an upper bound on memory usage." The consequence is that the safest Ada variants do not allow dynamic memory management at all.

But the next step down is to do the memory management in an isolated module of your code, which is then supposed to be vetted thoroughly.

Vanilla Ada (i.e. not the safest variant) does provide RAII for dynamic management of resources in general.