Technical Information › SVCUPDTE

SVCUPDTE

The operating system maintains a record of updates that users of the SVC table update service make to the SVC table. APF‑authorized requesters can invoke this service with the SVCUPDTE macro. When the SVC table is updated by using SVCUPDTE, the previous SVC table entry is captured in the SVC update recording table, with information about the program that issued the SVCUPDTE.

The SVC update recording table has a single entry for each of the 256 standard SVC numbers, just as the SVC table contains one entry per SVC. Because there is only one entry for each SVC, the update recording table retains information about only the most recent change to the corresponding SVC table entry. However, an SVCUPDTE count is maintained in the recording table entry that contains the total number of times the associated SVC was modified or replaced by successive SVC updates.