Understanding the recovery environment

When you write a recovery routine, you must take into consideration a number of environmental factors that are present when the recovery routine gets control, and that are present when a retry routine gets control. This information discusses environmental factors in two broad categories, distinguishing register contents from all other environmental factors:

• Register contents.
  Recovery routines are interested in register contents at the following times:

  • When the error occurs

    When the recovery routine gets control, certain fields in the SDWA contain the register contents at the time the error occurs. SDWAGRSV contains the contents of the GPRs; SDWAARER contains the contents of the ARs.

  • On entry to and return from the recovery routine

    See Register contents on entry to a recovery routine and Register contents on return from a recovery routine for details.

  • On entry to the retry routine

    See Register contents on entry to a retry routine for details.

• All other environmental factors.
  The other environmental factors important in a recovery environment are:

  • Authorization: problem state or supervisor state, PSW key, and PSW key mask (PKM)
  • SDWA storage key
  • Dispatchable unit mode
  • Cross memory mode
  • AMODE
  • ASC mode
  • Interrupt status
  • Dispatchable unit access list (DU-AL)
  • Locks
  • Program mask
  • Condition of the linkage stack
  • Authorization index (AX)
  • Extended authorization index (EAX)

This information discusses each of the environmental factors, and makes distinctions, where necessary, that depend on the following:

• Whether the system provided an SDWA
• Whether you have an ESTAE-type recovery routine or an FRR
• Whether you are dealing with the recovery routine or the retry routine.