Message looks like this for 256M:
SYBCTI665P 1 active tasks of 262144K possible; CORE MAX=492047K MAXTAPE=1
SYBCTI665P 7 ACTIVE TASKS OF 262144K POSSIBLE; CORE MAX=2052088K MAXTAPE=8
In both of the above examples, the value "262144K" is indicating the amount of storage designated per task (OPCORE).
So, that number/value is displayed in "K". Therefore, if you divide 262144K by 1024, you get 256M ... so 262144K is equivalent to 256M.
If you multiply 262144K by 1024 you get 268435456 -bytes ... 268435456-bytes=262144K=256M
There is a cosmetic bug on the re-display of the HiDRO defaults panel for the OPCORE value where the panel only re-displays 8-bytes of the stored value (internally the value entered is converted from "K" or "M" and stored in bytes). On this panel they never envisioned that you could specify 256M for a single task ... it was assumed it would be something less than 16M.
However, my point with verifying the value in the SYBCTI665P was to show you that your defaults are as you want them ... the task OPCORE is now defaulting to 256M.