how is the /proc/[pid] directories created?

["remaper" <yp.fangdong@xxxxxxxxx>]

hi, everyone

when we start a new program, how and where(source code) is the relative /proc/[pid] directory create?ÿôèº{.nÇ+?·?®?­?+%?Ëÿ±éݶ¥?wÿº{.nÇ+?·¥?{±ýûz÷¥þ)í?æèw*jg¬±¨¶????Ý¢jÿ¾«þG«?éÿ¢¸¢·¦j:+v?¨?wèjØm¶?ÿþø¯ù®w¥þ?àþf£¢·h??â?úÿ?Ù¥