Locating modules and control blocks in a dump

Many vital DFSMShsm data areas are located by their addresses in the management communication vector table (MCVT). Figure 1 shows how two base items (MCVT, ARCESD) can be located when the dump includes low storage.

Note: The following information and examples refer only to the DFSMShsm primary address space. For dumps occurring in the ABARS secondary address space, contact the IBM® Support Group for further assistance.

Figure 1. Locating the MCVT and Module ARCESD

When the low storage is not available, it is helpful to know that the MCVT follows the module ARCCBS, and that ARCESD and ARCCBS are ordered respectively as the first two modules of the DFSMShsm load module ARCCTL.

The first occurrence of the word MCVT is in ARCESD (see the following example), and the associated address gives the actual location of the MCVT.

All DFSMShsm modules and major DFSMShsm control blocks, such as the MCVT, the management control record (MCR), and the backup control record (BCR) are each pointed to by the ARCESD module.

Examples: These dump examples were obtained and processed by using IPCS:

This example, a segment of a dump, shows the beginning of ARCESD. It contains eight-byte module name fields followed by corresponding four-byte address fields for each DFSMShsm module. By using this information, you can efficiently locate these modules within the dump. Note that even though most modules have their names at the beginning of the module, ARCESD does not.
This example demonstrates how to locate a specific module in the dump (in this case ARCABNMB). The module name and its corresponding address are located in ARCESD, and then the leftmost column is scanned until this address is again located.
Here is another example of how to locate a specific module in the dump (in this case ARCALOG).

The MCVT, in addition to storing flags, also contains pointers of work queues and chained lists. Figure 2 shows some of the useful work queues and global data areas. Note that the MWEs in CSA (pointed to by MQCTMWEH) represent only those requests from the host started with HOSTMODE=MAIN.

Figure 2. Using the Management Communication Vector Table