The ALIGN keyword is used to align float, integer, and unsigned subfields. When ALIGN is specified, 2-byte subfields are aligned on a 2-byte boundary, 4-byte subfields are aligned on a 4-byte boundary and 8-byte subfields are aligned on an 8-byte boundary. Alignment may be desired to improve performance when accessing float, integer, or unsigned subfields.
Specify ALIGN on the data structure definition. However, you cannot specify ALIGN for either the file information data structure (INFDS) or the program status data structure (PSDS).
Alignment occurs only to data structure subfields defined with length notation and without the keyword OVERLAY. A diagnostic message is issued if subfields that are defined either with absolute notation or using the OVERLAY keyword are not properly aligned.
Pointer subfields are always aligned on a 16-byte boundary whether or not ALIGN is specified.
See Aligning Data Structure Subfields for more information.