Request handling for the large frame area system limit

The system limits the amount of online real storage that can be reserved in the large frame area for 1 MB and 2 GB pages. The system applies this limit differently depending on which of the two syntax forms is used for the LFAREA request. The two syntax forms cannot be combined.

If the LFAREA request is specified using xM, xG, xT, or x% syntax, to reserve 1 MB pages:

The system limit is calculated as: (80% * online real storage available at IPL) – 2G
The value specified by xM, xG, xT, or x% is applied toward the limit, with the percentage calculated as (x% * online storage available at IPL) – 2G.
If the limit is exceeded, the system rejects the request and prompts for re-specification of the LFAREA request.

If the LFAREA request is specified using the 1M= or 2G= syntax form, to reserve 1 MB or 2 GB pages (or both):

The system limit is calculated as: 80% * (online real storage available at IPL – 4G)
The system limit is imposed on the sum of the 1 MB and 2 GB pages
For the form 1M=(a) and 1M=(a%) and 2G=(a) and 2G=(a%), the value specified for a or a% is applied toward the limit, with the percentage value calculated as a% * (online storage available at IPL – 4G)
For the form 1M=(a,b) and 1M=(a%,b%) and 2G=(a,b) and 2G=(a%,b%), the value specified for b or b% is applied toward the limit, with the percentage value calculated as b% * (online storage available at IPL – 4G)
For any percentage request that is by definitively over 80%, the system will reject the request as a specification error and prompt for re-specification of LFAREA, regardless of the prompt or noprompt specification. The following examples are specification error cases:
- LFAREA=(1M=81%)
- LFAREA=(1M=(40%,20%),2G=(41%,20%))
- LFAREA=(1M=(1,0),2G=80%) )
If the 1M= or 2G= request is specified (or both), and the applicable value or sum of values exceeds the system limit, and prompt is also 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.
For any request containing a target and minimum specification where the target or sum of targets is above the system limit, the system will attempt to satisfy the request at or less than the system limit, provided that the request can be satisfied at or above the minimum values specified.