Pageable Link Pack Area (PLPA)

  • It’s defined in SYS1.PARMLIB(LPALSTxx).
  • It’s an area of Common Storage that is loaded at IPL time.
  • This area contains SVC routines, access methods, and other READ-ONLY System Programs, along with any READ-ONLY reenterable user programs selected by an installation that can be shared among users of the system.
  • There cannot be PDS/E data sets in the LPALST concatenation.
  • Modules must be reenterant and executable.
  • Programs in the PLPA are shared among users of the system.
  • It is desirable to place all frequently used refreshable SYS1.LINKLIB and SYS1.CMDLIB modules in the PLPA.
  • ASM maintains records that have pointers to the PLPA and Extended PLPA pages in the PLPA data set.
  • During quick-start or warm-start IPLs, the system uses the pointers to locate the PLPA and Extended PLPA pages. The system then rebuilds the PLPA and Extended PLPA page tables, and uses them for the current IPL.
  • If CLPA is specified during the IPL, a Cold start is then performed. The PLPA storage is deleted and made available for system paging use. A new PLPA and Extended PLPA are then loaded, and pointers to the PLPA and Extended PLPA pages are recorded in the PLPA page data set.
  • The LPALST concatenation can have up to 255 extents. If you specify more data sets than the concatenation can contain, the system truncates the LPALST concatenation and issues messages that indicate which data sets were not included in the concatenation.


  • PLPA and Extended PLPA contain all the members of SYS1.LPALIB and any other libraries that are specified in the active LPALSTxx.
  • The modules must be refreshable.
  • Load modules with RMODE 24 are placed in the PLPA (below the “line”), while those with RMODE of any are placed in the Extended PLPA (above the “line”).
  • If one or more LPALSTxx members exist, and the system can open the specified data sets successfully, the system uses the LPALST concatenation to build the PLPA (during Cold starts and IPLs that include the CLPA option). Otherwise the system builds the PLPA from only those modules named in the SYS1.LPALIB.

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