For this topic's original documentation, see the DSZ Variable - Get Available User Memory.
While PRO/5 uses a fixed workspace allocated by the
parameter or the START verb, BBj uses whatever memory was allocated to
the JVM in which it is running.
For the convenience of legacy PRO/5 applications that may be sensitive to the value of the DSZ variable, the BBj DSZ variable returns a value equal to 256 times the most recent START value. If the START verb has never been used, it returns a value equal to 256 times the command-line
-m parameter. If the command-line
-m parameter was not specified, it returns a value equal to 256*4096 (1048576).
In PRO/5, DSZ returns the amount of available memory (data size), and is a stable and deterministic value -- if you START PRO/5 with a certain amount of memory and allocate a given set of variables, DSZ will return a predictable value.