Request handling for insufficiently contiguous online real storage

In some cases, the LFAREA request cannot be satisfied even though it does not exceed the system limit. For example, real storage could be configured in such a way that some offline areas are interspersed among online areas, preventing the system from locating enough contiguous storage areas that start on a 2 GB boundary to use for the set of 2 GB pages.

When the LFAREA request is specified using the xM, xG, xT, or x% syntax form to reserve 1 MB pages:
  • For the syntax form xM, xG, and xT, the value specified for x is the target amount of real storage to reserve for 1 MB pages in the large frame area.
  • For a percentage request, the amount is calculated as: (percent * online real storage at IPL) – 2 GB
  • Once calculated, the percentage request is rounded down to the nearest 1 MB boundary.
  • If rounding down the percentage request results in zero, the system will reserve zero pages in the large frame area and continue with the IPL.
  • If the amount of storage required to satisfy the request cannot be located, the request will be satisfied at less than the requested amount and the system will then continue with the IPL.
When the LFAREA request is specified using the 1M= or 2 GB= syntax form to reserve 1 MB or 2 GB pages (or both):
  • For the form 1M=(a) and 1M=(a%) and 2G=(a) and 2G=(a%), the value specified for a or a% is both the target and the minimum amount of real storage that the system is to reserve for 1 MB or 2 GB pages in the large frame area.
  • For the form 1M=(a,b) and 1M=(a%,b%) and 2G=(a,b) and 2G=(a%,b%), the value specified for a or a% is the target amount, and b or b% is the minimum amount of real storage that the system is to reserve in the large frame area.
  • For a percentage request, the amount is calculated as: percent * (online real storage at IPL – 4G)
  • Once calculated, the 1M= or 2G= percentage request is rounded down to the nearest respective 1 MB or 2 GB boundary.
  • If rounding down the percentage request results in zero, and prompt is specified (either explicitly or by default), the system will issue a prompt to re-specify LFAREA. Otherwise, when noprompt is specified, the LFAREA parameter is ignored and the system will reserve zero 1 MB pages and zero 2 GB pages in the large frame area, and then continue with the IPL.
  • If the 1M= or 2G= request cannot be satisfied with at least the minimum amount requested, and prompt is specified (either explicitly or by default), the system will issue a prompt to re-specify LFAREA. Otherwise, when noprompt is specified, the LFAREA parameter is ignored and the system will reserve zero 1 MB pages and zero 2 GB pages in the large frame area, and then continue with the IPL.

Default Value: None (No LFAREA is defined)

Associated Parmlib Member: None

Parent topic: LFAREA