How can we know the actual total amount of 31-bit stg used by a CV?
DC390020 message does not appear to include everything allocated in 31-bit (XA) storage.
This is true because some 31-bit opsys stg allocations are done After the startup messages DC390005 thru DC390008
DC390020 Vnnn TOTAL AMOUNT OF XA STORAGE includes all 31-bit pools plus the fixed control block areas and system tables that reside in 31-bit stg.
This does not include the 31-bit storage used for BUFFERs as they are allocated after this point in startup.
If you do a LOOK DMCL, there is a section on Buffer sizes and it will show how much
31-bit opsys stg is used for buffers.
0 Bytes used for CV buffers in DC storage
15,867,132 Bytes used for CV buffers in OS storage
15,867,132 Bytes used for CV DMCL Buffers
this plus the TOTAL AMOUNT OF XA STORAGE is the real total 31-bit stg a CV uses.
You should be sure this total is significantly less than the maximum of 2 GB for 31-bit stg in an LPAR. .
One more factor that could add to this is SCRATCH if it is allocated in 31-bit.
SCRATCH is one of the few things that can be allocated in 64-bit address so in IF you define it to use 64-bit storage and your system has 64-bit storage capabilities, then SCRATCH will not add to the amount of 31-bit stg used by the CV.
In the following example SCRATCH is allocated in 64-bit
Total number of pages 8075 Location ANY Storage
Page size 5064 Storage address 00000050 00000000
Primary extent #pages 8075 Primary extent size 39 MB
Secondary extent #pages 8075 Secondary extent size 39 MB
Storage limit #pages 8075 Storage limit size 39 MB
PUT scratch requests 4419 Scratch Areas active 1
GET scratch requests 208 Scratch Areas created 17
DELETE scratch requests 4139 HWM concurrent Scr. Areas 6
Pages in use 98 HWM pages in use 103
Pages in use percentage 1% HWM pages in use percentage 1%
Buffers N/A HWM pages in use for 1 S.A. 100
Pages found in buffer N/A HWM pages found for 1 S.A. N/A
Pages written N/A HWM pages written for 1 S.A. N/A
Pages read N/A HWM pages read for 1 S.A. N/A
If SCRATCH is allocated in 31-bit storage then it must be added to the DC390020 and Bytes used for CV buffers in OS storage AND again the total should be significantly less than 2GB to avoid system paging.
The system trace table (SYSTRACE) is also allocated later in the startup process and not included in the startup message, so it should be added to the DC390020 storage amount, see article 257704 - IDMS SYSTRACE table size and startup messages DC390020 DC390007