Creating and sizing the 64-bit storage pool

Creating the 64-bit storage pool is a system definition task. Before you can specify an appropriate size on the ACBIN64 parameter in the DFSDFxxx member of the IMS PROCLIB data set, you must perform some calculations.

You can make your calculations based either on DASD allocation or on the sizes of the 31-bit non-resident pool sizes.
To calculate how much 64-bit storage must be allocated for PSB and DMB ACB members, calculate how much storage is being used for all the non-resident PSBs and non-resident DMBs in the ACB library. DEDB DMBs always reside in 31-bit storage. Since DMBs and PSBs both reside in the same 64-bit pool, sufficient storage must be allocated to accommodate all these members.
The following are some examples:
  • The current DASD space allocation for all the non-resident PSBs and non-resident DMBs in the ACB library is 2150 cylinders on a 3390-9, which is approximately 1.9 GB of DASD space. To have sufficient space to include as many ACB members as possible in the 64-bit pool, specify ACBIN64=2.
  • There are 57 000 ACB members in the ACBLIB data set. The cumulative size of these ACB members is approximately 850 MB. The size of the non-resident DMB pool is 250 MB. The size of the non-resident PSB pool is 300 MB. Therefore, specify ACBIN64=1.