Number of tracks = (A + B) / T

A

is the number of 1403 UCS images, 3211 UCS images, 3211 FCB images, 3525 data protection images, 3890 SCI programs, 3800 FCB modules, 4248 FCB images, 3262 Model 5 FCB images, 3800 character arrangement tables and 3800 library character sets (including images or modules supplied by you or IBM).

IBM supplies twelve 1403 UCS images, five 3211 UCS images, four 3211 FCB images, one 3800 FCB image, one 4245 UCS image table, one 4248 UCS image table, or eighty-four 3800 character arrangement tables, twenty 3800 Model 1 library character data sets, twenty 3800 Model 3, 6, and 8 library character sets, and graphic character modification modules.

Restriction: IBM supplies no 4245 or 4248 UCS images in SYS1.IMAGELIB. The 4245 and 4248 printers load their own UCS images into the UCS buffer at power-on time. IBM does supply 4245 and 4248 FCB images, which may be used.

B

is (V + 600) / 1500 for each 3800 graphic character modification module and library character set module, each 3800 copy modification module, 4245 UCS image table, 4248 UCS image table, and each 3890 SCI program that is more than approximately 600 bytes.

V

is the virtual storage requirement in bytes for each module.

The virtual storage requirements for the IBM-supplied 3800 graphic character modification module containing the World Trade National Use Graphics are 32420 bytes for Model 1 and 55952 bytes for Model 3, 6, and 8. The virtual storage requirements for the IBM-supplied 3800 library character sets for the Model 1 are 4680 bytes and 8064 bytes for the Model 3, 6, and 8.

T

is the approximate number of members per track, depending on type of volume. Because of the overhead bytes and blocks in a load module, the difference in space requirements for an 80-byte module and a 400-byte module is small.

These constants assume an average member of 8 blocks, including a file mark, with a total data length of 800 bytes. For example, on a 3380 with 523 bytes of block overhead, the assumed average is 4984 bytes. If a different average member data length and average number of blocks per member are anticipated, these constants should reflect the actual number of members per track.

To determine the number of members per track, divide the average member length, including block overhead, into the track capacity for the device, see Table 1.

Table 1. Members per track (T) for various devices

T	Device Type
17	3380, all models
20	3390, all models
16	9345, all models

The result, (A + B) / T, is the track requirement.

Number of directory blocks = (A + C + D) / 6

A

is the same value as A in the track requirement calculation.

C

is the number of modules used to calculate B, when calculating the track requirement.

D

is the number of aliases. The IBM-supplied 1403 UCS images have four aliases and the IBM-supplied 3211 UCS images have six aliases. If you are not going to use these aliases, you can scratch them after the system is installed.

• For more information about printer-supplied UCS or FCB images, see z/OS DFSMSdfp Advanced Services.
• For information about track capacity for DASD, see z/OS DFSMS Macro Instructions for Data Sets.