Virtual Storage Required for the BDT Address Space

The virtual storage required for the BDT address space is the sum of the virtual storage required for modules plus the virtual storage required for data areas, as shown in the following table. (All values are in decimal.)

Activity	Virtual Storage Required for Modules	Virtual Storage Required for Data Areas
Starting BDT	277K bytes^{See note 1}	19K bytes + (300 bytes × no. of BDTNODE statements) + (136 bytes × total no. of VLUs) – (216 bytes if file-to-file)^{See note 2}
Activating the SNA manager	58K bytes	1K bytes + (644 bytes × (no. of file-to-file BDTNODE statements – 1)) + (644 bytes × no. of SNA NJE BDTNODE statements) + (112 bytes × total no. of VLUs) + (32 bytes × total no. of VLUs)^{See note 3}
Transferring a sequential data set	7K bytes^{See note 4}	(2419 bytes × no. of active transfers) + (376 bytes × no. of active transfers) + (408 bytes × no. of active transfers)
Transferring a partitioned data set	10K bytes^{See note 4}	(990 bytes × no. of active transfers) + (376 bytes × no. of active transfers) + (408 bytes × no. of active transfers)
Sending a SNA NJE job or output	8K bytes^{See note 4}	(975 bytes × no. of active transfers) + (376 bytes × no. of active transfers) + (408 bytes × no. of active transfers)
Receiving a SNA NJE job or output	6K bytes^{See note 4}	(1171 bytes × no. of active transfers) + (376 bytes × no. of active transfers) + (408 bytes × no. of active transfers)

Notes:

277K bytes includes:
- 25K bytes for the following modules in the PLPA: BDTLP, BDTSSBDT, BDTSSEOM, BDTSS34, and IGX00034.
- 5K bytes for the sample required (authorization) exit routines provided by IBM in SYS1.SBDTSAMP: BDTUX25, BDTUX26, BDTUX27, BDTUX28, BDTUX29, and BDTUX31.
A more detailed formula is 19K bytes +:
- For the LCT control block: (136 bytes × (no. of file-to-file BDTNODE statements – 1) + (no. of VLUs)) + (136 bytes × (no. of SNA NJE BDTNODE statements + no. of VLUs))
- For the RLT control block: (84 bytes × (2 × no. of file-to-file BDTNODE statements – 1)) + (84 bytes × (2 × no. of SNA NJE BDTNODE statements))
A more detailed formula is 1K bytes +:
- For the LCB control block: (644 bytes × (no. of file-to-file BDTNODE statements – 1)) + (644 bytes × no. of SNA NJE BDTNODE statements)
- For the DCL and LCTE control blocks: (144 bytes × no. of file-to-file VLUs specifying compression) + (112 bytes × no. of file-to-file VLUs without compression) + (144 bytes × no. of SNA NJE VLUs)
This storage is for DAP modules, which are kept in storage after they are used the first time. Subsequent transfers do not cause them to be reloaded.

Additional storage is required for the CSA (which VTAM and JES3 use as staging areas and for reading and writing to spool), SQA, LSQA, SWA, and subpools 229-230. Cell pool storage is allocated from user subpools 10-21 (see Table 1). This additional storage is configuration and task dependent.