Performing Track Calculations (TRKCALC macro)

The TRKCALC macro performs DASD track capacity calculations. This macro is intended for EXCP applications and other advanced applications. You can use TRKCALC to determine:

The number of equal-length records that can be written on a track
The total track capacity
Whether a record can be written in the space remaining on a track and return the new track balance
What the track balance would be if the last record were removed from a track
The length of the longest possible record that can be written to a track.

The TRKCALC routine issues no SVC instructions or I/O. TRKCALC can be called in an SRB routine or in TCB mode. It can be called in 24-bit or 31-bit addressing mode and in supervisor or problem state.

TRKCALC works equally well for any track. It does not use the address of the track.