I am a little confused by "overlay storage" Are you asking can it cause an abend by overlaying storage?
Or are you asking if when you deactivate/active SSI does it replace what was there with new information? Could you clarify more of what direction you question is going? Is there a problem or issue or concept you are trying to handle? I did a quick internet search on IBM SSI DYNAMIC and came up with this presentation from Share 2004. Maybe it can help http://www-03.ibm.com/support/techdocs/atsmastr.nsf/5cb5ed706d254a8186256c71 006d2e0a/0d43ec382b0f111c8625730f0071eef7/$FILE/s2852pr.pdf Dynamic subsystems are those subsystems that can be defined in one of the following ways: Processing the keyword format IEFSSNxx parmlib member during IPL Issuing the IEFSSI macro Issuing the SETSSI system command. Subsystems have the choice of being dynamic. Subsystems that are not dynamic can be defined only at IPL using the positional form of the IEFSSNxx parmlib member, in which case, they cannot use dynamic SSI services. In addition to its role in communicating with subsystems, the SSI provides a set of authorized system services that are available only to dynamic subsystems that installations, applications and subsystems can invoke to: Define (add) a new subsystem dynamically (without requiring an IPL) Activate a subsystem that is already defined Deactivate a subsystem that is already defined Store and retrieve subsystem-dependent information Define subsystem options, which include deciding: If a subsystem can respond to the SSI commands Which subsystem a subsystem should start under. Query subsystem information Define and modify the response of a subsystem to function requests. Defining or adding a subsystem is primarily a way of making the subsystem's unique name known to the system. A subsystem is active when it is ready to process requests that the SSI directs to it. To deactivate a subsystem, the subsystem informs the SSI that it is no longer accepting requests. For example, a subsystem may request that it be deactivated to update the list of function requests that it supports, or to respond to a problem. The dynamic SSI services reject any requests to manipulate subsystems that were not defined dynamically. The services that allow installations, applications and subsystems to define and modify the response of a subsystem to function requests replace and enhance the existing IEFJSVEC service. You can still use the existing IEFJSVEC service, which is described in Using IEFJSVEC with Your Subsystem, however IBMR recommends that you use the services described in Services for Building and Using Your Subsystem instead of IEFJSVEC. These services provide an easier way to define or change the functional response of a subsystem. Lizette -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of mf db Sent: Wednesday, September 11, 2013 12:33 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: SSI update Hello All, I am trying to understand if Dynamic SSI update can overlay the storage. Could someone please shed some light on dynamic SSI update. Peter ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN