The POINT macro causes the next READ or WRITE operation to position at the beginning of a PDSE member, or anywhere within a PDSE member. The POINT macro uses the track record address (TTRz), which you can obtain from NOTE, BLDL, or a BSAM read of the directory, to position to the correct location. If positioning to the beginning of a member, the z byte in the TTR must be zero. The POINT macro establishes a connection to the PDSE member (unless the connection already exists).

The POINT macro positions to the first segment of a spanned record even if the NOTE was done on another segment. If the current record spans blocks, setting the z byte of the TTRz field to one lets you access the next record (not the next segment).

You can position from one PDSE member to the first block of another member. Then you can position to any record within that member. Attempting to position from one member into the middle of another member causes the wrong record to be accessed. Either data from the first member will be read, or an I/O error will occur. When the PDSE is open for output, using the POINT macro to position to a member other than the one being written results in a system ABEND.

If you have insufficient access authority (you have only RACF execute authority) or if the share options are violated, the POINT macro fails with an I/O error. See Sharing PDSEs.

Related reading: For more information about the POINT macro, see z/OS DFSMS Macro Instructions for Data Sets and Using the POINT Macro to Position to a Block.