Where can I find the record layout for the history file? Something that shows what the various fields are in the record, what the format is of each field, and so forth.
Release : 12.0
The macro HSTDSECT provides the record layout of the history file (default HISTORY_OUT_DD=XCOMHOUT).
Documentation reference: SMF Record and History File
To create a history report the XCOMJOB TYPE=HISTORY was introduced with XCOM r11.5 and above. Prior to that users would have to create a report using their own program using the HSTDSECT.
The TYPE=HISTORY uses members XCOMEHRP and XCOMESTT found in the CBXGSAMP library.
PARM Parameters - TYPE
XCOMJOB Sample JCL