The exit routines are executed partially or completely under the system administrator ID TSOS (depending on how the data center is organized). For this reason, special care must be taken while programming. The following rules must be strictly adhered to:
The program must conform to BS2000 conventions for program linkage, i.e. the start and end must be structured as follows.
MARENEXn CSECT
STM 14,12,12(13)
:
:
LM 14,12,12(13)
BR 14
In an XS environment, the exit routines must contain AMODE ANY and RMODE ANY and conform to the XS programming rules.
Fields marked in the catalog record (macro MARENA DSECT) as “unused”, “reserved” or as “MAREN-internal field” must not be used by the exit routines. In particular, the fields LAFUNKNM and LAFUNKFL must not be modified.
Most exits are not permitted to change certain catalog entry fields, since correct processing would not otherwise be guaranteed. If this nevertheless happens, the loaded program is terminated with the message
MARCP27.The catalog entry fields affected are indicated in the descriptions of the individual computer center exits.
Programming rules are described in the “System Exits” manual [7].
Modification of date fields
Data fields can only be edited in ISO4 format (with four-digit year specification).