Return the address of a modifiable logger managed by this logger manager configured with the specified record buffer. Optionally specify a scratchBufferSize for the logger's user-accessible message buffer. If scratchBufferSize is not specified, the value configured at construction is used. Note that this method is primarily intended for use in multi-threaded applications, but can be used to partition logging streams even within a single thread. Also note that ownership of buffer is not transferred, and hence, will not be destroyed (or otherwise affected) after the logger is deallocated.