Yes, in routine B000RMSG in your customized XCOMSEC module, which extracts and writes messages returned from the security product, you need to modify the "STORAGE RELEASE" macro call to add a "SP=25" parameter.
The resultant STORAGE RELEASE in B000RMSG should end up looking like this:
STORAGE RELEASE, +
The SP=25 is only relevant to this one STORAGE RELEASE call. The other storage does not need this parameter, as only the messages returned by the security product are placed in storage subpool 25.