System activity keypoints

The recovery manager controls the recording of keypoint information, and the delivery of the information to the various resource managers at emergency restart.

The recovery manager provides the support that enables activity keypoint information to be recorded at frequent intervals on the system log. You specify the activity keypoint frequency on the AKPFREQ system initialization parameter. Activity keypoint information is of two types:
  1. A list of all the UOWs currently active in the system
  2. Image-copy type information allowing the current contents of a particular resource to be rebuilt

During an initial phase of CICS® restart, recovery manager uses this information, together with UOW-related log records, to restore the CICS system to its state at the time of the previous shutdown. This is done on a single backward scan of the system log.

Frequency of taking activity keypoints: You are strongly recommended to specify a nonzero activity keypoint frequency. Choose an activity keypoint frequency that is suitable for the size of your system log stream. Note that writing activity keypoints at short intervals improves restart times, but at the expense of extra processing during normal running.

The following additional actions are taken for files accessed in non-RLS mode that use backup while open (BWO):
  • Tie-up records are recorded on the forward recovery log stream. A tie-up record associates a CICS file name with a VSAM data set name.
  • Recovery points are recorded in the integrated catalog facility (ICF) catalog. These define the starting time for forward recovery. Data recorded on the forward recovery log before that time does not need to be used.