Perform calculations and conversions with 28-bit cylinder addresses (TRKADDR macro)

TRKADDR is an assembler macro that performs conversion and compare operations on DASD track addresses in the form CCCCcccH, where CCCC is the 16 low order bits of the cylinder number and ccc is the 12 high order bits of the cylinder number. This is referred to as a 28-bit cylinder address. TRKADDR works equally well with track addresses that contain a cylinder number less than or greater than 16 bits. It works with all DASD types that are supported by z/OS®. Its functions include:

Calculate the relative track number on the volume
Compare two track addresses
Extract the 28-bit cylinder number
Extract the 4-bit track number
Increment the track address by one track and increments the cylinder number if necessary.
Normalize cylinder number to permit comparing one cchh against another
Convert a relative track number to a 28-bit cylinder address
Set the cylinder number in a 28-bit track address
Convert a normalized track address into an absolute 28-bit track address.

Unless otherwise stated, you can specify any registers from 0 to 15 except that register 0 cannot be used to address storage. TRKADDR does not use any other registers, even register 13. You can invoke TRKADDR in 24-bit, 31-bit or 64-bit mode. If you use the SYSSTATE macro with AMODE64=YES in an earlier source code statement, then TRKADDR might generate more efficient code.