Selectable unit packaging is a feature of GCOS that allows certain parts of the operating software to be maintained under control of the file management supervisor (FMS) rather than as a part of the system software. This allows these items to be maintained on-the-fly without a system boot to install new versions or to fix errors. In addition, it is possible to dispose low use software to removable disk packs, thus allowing more on-line space for general use.
Packages presently installed as Selectable Units are:
PL1 CBL74 IDS2
As new software releases are received for other units eligible for this treatment, they will be placed on the system as selectable units also. Possibilites are:
GMAP 355MAP FORTRAN COBOL ('68) IDS
When the system determines that a unit is installed selectable, an access is made to a search rule file to locate the desired software. In the case of a program load (GECALL), the default search rule file is ..SYS_<unit_name>/PROC.SR and for a program link (GELOAD), ..SYS_<unit_name>/LIB.SR. These search rule files are merely lists of FMS pathnames pointing to the files to be searched. They may be ASCII type 6 (time sharing text) or BCD type 2 (card images). Records are limited to 80 characters, and there must be only one rule per image. The number of search files is limited only by the available Peripheral Allocation Table (PAT) space in the user process.
It is possible for a user to have his own search rule file. If this is the case, it must be allocated to the relevant activity with a file code of $* for GECALL and *$ for GELOAD.
Searches conducted by the system loader (GECALL) for linked programs when search rule files are present are conducted in the following order:
Searches conducted by the link loader (GELOAD) for subroutine libraries are as follows:
Search rule files are made up of records that begin in column one and are free form. The syntax required is:
<pathname>[ <file code>]
The pathname is the FMS path to the file to be used for the search. Pathnames must not contain more than nine (9) catalog names. The optional file code may be assigned by the rule builder. If no file code is supplied, the system will create unlikely file codes for you. We recommend that you let the system do this.
Comments may be included in search rule files by placing the characters "/*" in columns 1 and 2 of the record. The balance of the card image will be treated as comments. Inclusion of a large number of comments will slow the search considerably, so we recommend that there be few to none of them.
This facility is only available in batch (more's the pity).
Own code search rule perm files in media code 6 (TSS ASCII) don't work in GELOAD. The program aborts with an F7 (illegal op code). If own code subroutine search rules are needed, use CARD (media 02, 80 characters per record) files or put them in the job stream using $DATA *$.
Copyright © 1996, Thinkage Ltd.