Statement Summary

Table 1. BUFFER Summary
Variable	Value
Required/Optional Statement	Optional
Statement Default	`BUFFER,BUFSIZE=4084,PAGES=(1024,128,512), GRPSZ=30,MINBUF=16,SPLIM=(10,25), TRUNC=YES`
Placement in Initialization Stream	This statement must appear before the ENDJSAM statement.
Coding Considerations	If you change the BUFSIZE parameter and do not reformat the spool data sets before the next cold start, include FORMAT statements in the initialization stream during the next cold start.
Performance Considerations	In selecting the size of the buffer pool, make sure the size is large enough for all functions to be active at the same time. Also, it is recommended that you make the buffer pool larger than the value you calculate. The larger buffer pool will better accommodate bursts of I/O activity. If virtual storage in the JES3 global address space is not constrained, the recommended buffer size is 4084. Buffers do not span page boundaries; therefore, specifying 2036 or less provides two buffers per page. Specifying a larger value provides one buffer per page. These recommended values optimize virtual storage usage but do not optimize spool usage.
Security Usage	None
Initialization Stream Overrides	The GRPSZ and SPLIM parameters on the SPART statement override the GRPSZ and SPLIM parameter on this statement. The TRUNC parameter on the SYSOUT statement overrides the TRUNC parameter on this statement for the specified SYSOUT class.
Restart or Command Modification	Cold start to change the size of a buffer (BUFSIZE). Warm start to replace a spool data set (WR) and to modify the GRPSZ and SPLIM parameters. Hot start with refresh to modify the PAGES, MINBUF and TRUNC parameters. All other parameters are syntax checked only; the value from the last warm or cold start will be used. The statement is accepted, but ignored by *MODIFY CONFIG.